GMAT dont test interrogative sentence - I couldn't find any in OG.
"Everyone" is singular. But here the subject-verb issue will only be applicable for "does" and not for "has/have" - "has" will be in its base form perfect aspect : have. So 3 is the correct one.
Consider these sentence to see how verb tense and subject-verb agreement take its form.
She might have been there.... - its not "has" here, always the first form of the verb represent tenses and signifies S-V agreement - here it is "might" - conditional past perfect tense
She has been there.... - here "has" is the first verb and hence take the tense and the S-V agreement. - present perfect.
All other verbs other than the first tense, will be in its plural base form.
This is how this works - You can convert this sentence to apply the above rules,
Everyone does has/have .... - so "does" take the S-V agreement and the tense and not has/have,which is in its base form. But please note, we generally don't write this type of sentence - but its not grammatically wrong.
Hope this helps !!
