Why the answer to Q27 is D?

This is the sentence: The combination of AR technology, geocaching and other novel techniques to create innovative active video games has potential personal and public health implications, the researchers noted. "The combination" is the subject "of AR of AR technology, geocaching and other novel techniques" is a prepositional phrase "has" is the verb so we know the blank can't be a conjugated verb. The rest of the sentence after the verb we can ignore. "to create innovative active video games" is what we call an infinitive clause, which are a type of subordinate clause. We can't use "creates" in the blank because "creates" is conjugated and we already know the verb of the sentence is "has". "Creating" is both a gerund and an active participle so you have to use context to know which is which. Looking at the sentence it's not a gerund. You can, in some cases, use an active participle here but it would mean the thing in the prepositional phrase was doing the creating and we know that's not the case. *People* are using these tools to create things. The tools themselves are not doing the creating. "Created" is both a past tense verb and a passive participle. It can't be a verb here because "has" is the verb. So that leaves "created" as a passive participle. The only way using "created" here is in combination with a preposition of some kind like "created by" or "created with" or "created from". The sentence would be grammatically correct but also wrong as the video games aren't creating AR technology. So we know "created" is wrong not only because it makes no sense but also because the answer would require a preposition.

In addition to the correct answers to your question already provided, the title of your post should be "Why is the answer to Q27 D?" not "why the answer to Q27 is D?".

Because they are using those three listed things "to create" new games.  It with be the same as saying "he needs sugar, flour, and eggs to make a cake". Hopefully that helps.

The sentence is awkward, but (D) is correct. I'll simplify the sentence to help make it more clear. "The \[approach\] to create games has potential, the researchers noted."

Phrase of purpose

I just want to say I think that's a really ugly sentence to have to work with. While, yes, it does have to be 'to create' it's absolutely horrible. Probably one of those passive voice science writing things but jeez....

to be fair to you bro, these advertisement style texts look jarring to me too.

If I remember correctly, the part **to create** is not an infinitive. In a way, it’s a shorten version of **in order to** (a subordinating conjunction)+Verb; used to express the purpose of something.

Put “creates” in the sentence and read it out loud. It doesn’t make any sense.

Simplify the sentence to "The techniques ___ games has implications." Then it becomes obvious. "The techniques creates games has implications." ❌ "The techniques creating games has implications." ❌ "The techniques created games has implications." ❌ "The techniques to create games has implications." ✅