I really don't know the answer

I'd drop the "o'clock" but "it's ten TO one" makes perfect sense in British English to mean 12:50.

The answer is to. Ten to one is this 12:50

'To' is correct, but you would just say 'ten to one' and end it there. Adding o'clock on the end sounds really unnatural, at least to me -- you would normally only use o'clock after the exact hour (like 'one o'clock', two o'clock' etc.)

I wouldn’t use any of them. I would just say it’s ten to one

10 to 1 is 12:50

It's to but we'd drop the O'clock bit usually.

Just to add, if it were rearranged to: "In ten minutes it'll be one o'clock. I need to buy lunch!" Then it would also work for me.

Native speaker here. Its a gibberish question but the only one that kind of works in "to", as in, if you drop the "o'clock" it works as "10 to 1". Still, very badly worded question.

You should select “to” because the sentence will become “It’s ten to one o’clock.”

O’clock is only used for whole hours. 1, 2, 3 o’clock, etc. It is never used when there are minutes to be said. For example, one thirty-five o’clock is wrong. Not just unnatural, but simply wrong. The term is a degeneration from “of the clock” which leads to the next point . . . “O’clock” is not used with the 24-hour system. Since 99.99% of the clocks have a 12-hour face, saying “thirteen o’clock” also is wrong. (I only once saw a 24-hour faceplate clock, and it was in a movie.)

“Ten to one” sounds normal to me. “Ten to one o’clock” sounds very strange to me. But I don’t know if it’s a mistake or some kind of regionalism.

"to" "until" and "before" also work.

"Ten til" (the hour) is a phrase used to tell time sometimes. It's more common among older people who grew up with analog clocks I would imagine, cause I rarely hear it now. I don't recall ever hearing the "o'clock" with it. "It's ten til 1." Or "it's a quarter til 2" (a quarter of an hour is 15 minutes) are ways you might hear time in this style. It may be a southern US thing, but I only hear people use the "o'clock" if they are only saying the hour. "It's 12 o'clock". "Be home by 9 o'clock." It tends to be omitted if you give the minutes. "It's 12:15." "Be home by 9:30."

Fundamentally the question is invalid. As it is constructed, to my ear none of the answers would ever be spoken by a native speaker. ‘To’ could be correct but only if “o’clock” is removed from the question. “Ten to one” is normal and used all the time. “Ten to one o’clock” - even if someone might be able to argue is *technically* not incorrect - is simply not used, and therefore sounds wrong. Very wrong! 

I think “ten to one o’clock” is perhaps technically correct but sounds awkward and you should instead say “ten to one.” We Omit the “o’clock” unless you’re talking about a whole hour (one o’clock, two o’clock, but never two thirty o’clock) so that’s what leads to the awkwardness with “ten to one o’clock”

This is a poorly written question, and I would use caution with whatever learning source it comes from. They are most likely expecting the answer, “to”. As has been said below, using “o’clock” here is an error that would lead to confusion in conversation with a native English speaker. The correct way to say this is: “It’s ten to one! I need to buy lunch!”

As others have said, you wouldn't say "o'clock" when you're using this construction. You'd say "ten to one." Fun fact, here in New England (Northeast US) many folks usually say "ten OF" or "quarter of" to mean ten/fifteen/whatever minutes before the hour. I never realized that was a regionalism until I had friends from Texas point it out and ask me about it.

Ten to one or ten till one

I would say till

"Ten *to* one" makes sense, but we'd rather say it without the "o'clock" to be honest. Still, it's a pretty old-fashioned way of communicating time

If you’re someone who says 10 to 1 instead of just saying 12:50, you are the cause of all the world’s problems.

It should be "to". Meaning 12:50. It's funny how "Ten to one o'clock" sounds unnatural with the "o'clock" at the end. "Ten to one" is much more natural, but it has so much less information, you'd expect it to cause so much confusion (is it a score? etc.) even amongst native speakers, but it doesn't really haha. At least not *a lot* of confusion.

None of the answers are correct.

"Ten to one o'clock" = it's 12:50

It's "to" as in "ten minutes to one," but that's based on lazy English. The actual phrase would be "ten (un)til one."

Why does ten to one o'clock sound perfectly natural and fine to me 😭?

Just think about it. Which one sounds like it makes sense? Is it ten in one o'clock? What could that possibly mean? Is it 10 on one o'clock? Again, doesn't make any sense. Is it 10 at one o'clock? No, it's one o'clock at one o'clock, not 10. Is it 10 to one o'clock? Yes. In 10 minutes, it will be one o'clock. To meaning on the way towards something. In this case it is 10 minutes towards one o'clock.

its to one i think.

ten to one ~~o'clock~~ (meaning ten minutes until one o'clock)

Nobody says ten to one o clock.

It's "to". The "o' clock" really shouldn't be there.

to

The correct answer is ‘to’ and drop the O’clock. I’m from the Midwest US and we’d just say 12:50. Saying 10 to One sounds old fashioned or British to me.

FYI, you can substitute "to" with "past" or "after" for time after instead of before the hour. For example, "it's a quarter after 6" means it's 6:15. ("Quarter" is shorthand for "quarter of an hour"), or "it's half past eight" is 8:30 (note that when using "half", it's always used with "past" but if you say "thirty", either "past" or "after" is fine). Or you can just read the time as it would be displayed on a digital clock, e.g. 1:32 would be read "one thirty-two". I believe the "[m minutes] to/after [h hours]" phrasing is from reading analog clocks.

Does anybody else say "ten of one"? Or is this just something my french canadian descended Rhode Island family made up???

To

No one ever says "ten to one o'clock." Ten to one? Sure. The o'clock just makes it clunky.

this sentence is bullshit

I can’t stand describing time this way. Just say the exact time! The syllabic difference cannot be THAT different. I wish it would go away.

IMO it should be ten TIL one, but out of these answers, it's ten to one.

Would you have cared to elaborate? Some say is to and some say none of them. Please help and Thanks for answering so far

None are correct

I really hate it when I ask for the time, and receive a simple math problem instead. Just tell me the time.