Problem: How does the sentence end?

With the goal to make cream, William called upon Aarons expertise however 
OPTIONS:
- William had no clue what to do.
- Aaron had no clue what to do.
Answer: Aaron had no clue what to do.

Problem: How does the sentence end?

Christopher asked Kyle to be his girlfriend last week but 
OPTIONS:
- Christopher was not eager to give an answer.
- Kyle was not eager to give an answer.
Answer: Kyle was not eager to give an answer.

Problem: How does the sentence end?

The mother always consulted a book for her pregnancy because the 
OPTIONS:
- pregnancy was very difficult.
- book was very difficult.
Answer: pregnancy was very difficult.

Problem: How does the sentence end?

Preston liked learning violin better than piano at music class, because the 
OPTIONS:
- piano hurt his back.
- violin hurt his back.
Answer:
piano hurt his back.