I doubt such a question would come in actual GMAT exam but as it appeared in 700+ here on GMATClub, we gotta do it anyway and we might as well learn a few writing styles
First 3 choices are essentially the same apart from the fact that they use 3 different writing styles:
A colon, a comma and a hyphen. Notice I used colon in this sentence
A) In 1987, when Tiffany was a hugely famous pop singer, journalists always used to ask her the same question: “Where do you see yourself in 10 years’ time?” -
A colon is always used after an independent clause. A colon must follow a complete sentence to give the sentence a sense of illustration. I think it is used in right way and we can keep this.B) In 1987, when Tiffany was a hugely famous pop singer, journalists always used to ask her the same question, “Where do you see yourself in 10 years’ time?” -
Here the comma seems to be separating 2 independent clause and creating a run-on sentence. A conjunction must be used. This choice can be rejectedC) In 1987, when Tiffany was a hugely famous pop singer, journalists always used to ask her the same question - “Where do you see yourself in 10 years’ time?” -
Hyphens are generally used to give the list of items (generally hyphens replace comma pairs). They might as well be used to separate 2 Independent clauses but I'd prefer (A) in this case over this choice.D) In 1987, when Tiffany was a hugely famous pop singer, journalists always used to ask her the same question
that “Where do you see yourself in 10 years’ time.” -
That is unnecessary over hereE) In 1987, when Tiffany was a hugely famous pop singer, journalists always used to ask her the same question whether you do see yourself in 10 years’ time. -
Whether is used for the choice. Easiest option to eliminate(A) is the correct answer.