You need to add where we find the answer from.. repost a question with a picture to this question
This is an example of a. feedback
Feedback is returning information back with a goal of showing understanding or analyzing the message that has been conveyed.
I think C is the most accurate choose to define elaboration
A. Yesterday, Leo had a __more difficult__ time sleeping than today.
B. is incorrect because it is incorrect to say one has "a difficultly time" doing anything; you have "a difficult time" doing something.
C. is incorrect because you can not say "most" when comparing something to something else; you can either say "It was the MOST difficult" or "It was MORE difficult than that."
The Answer to the question is A