Hi,

I'm with you on this one, I do think that this question is a bit weird.

The only thing I can think of is that they are asking about this anomeric carbon after reaction, as the leaving group attached to it is quite good. They then evaluate the hemiacetal and confirm that it can convert back and forth from hemiacetal/ketal resulting in the correct answer being D

Sometimes you get questions in your study that are like this, these questions are likely to be eliminated as test questions because very few to no people will get them right. I would expect most people to have picked A as it makes the most sense based off what you know (I would probably have picked A as well).

It may be an unsatisfying answer, but I think sometimes there are just strange questions.

I hope this helps!