Subscribe to The Chicago Manual of Style Online
Q. When a question introduces a list, should you use a question mark or a colon? Or both?
A. First, don’t use a question mark immediately followed by a colon, or vice versa (neither :? nor ?:); instead, use the stronger mark. Assuming a direct question, the question mark is usually stronger.
Which fruit would you be most likely to recognize by texture alone?
A signal like “the following” can be helpful in such cases: “Which of the following fruits . . .”
If you incorporate the list into a sentence, the question mark can follow the last item.
Which fruit would you be most likely to recognize by texture alone: bananas, apples, blueberries, cherries, or pineapples?
Especially for shorter sentences, a comma can be used instead of a colon to introduce the list.
Which fruit do you like best, bananas or pineapples?
Do you prefer apples or bananas or blueberries? [See CMOS 6.67.]