[Q]: How does the sentence end?

Brett wanted Nick to plant a tree in their yard but

[A]: Nick was going on a long vacation.

[Q]: How does the sentence end?

Derrick paid for their dinner but Steven wanted their's for free because

[A]: Derrick was generous.

[Q]: How does the sentence end?

Derrick was much more successful in life than Brett was because

[A]:
Derrick worked hard in school.