sentence: I hired a tutor and my brother went to extra classes. He ended up getting better grades than me so the OPTIONS:
- extra classes must be pretty effective.
- tutor must be pretty effective.
complete: extra classes must be pretty effective.

sentence: Erin was very comfortable outside during winter unlike Cynthia because OPTIONS:
- Erin had a very thin coat.
- Cynthia had a very thin coat.
complete: Cynthia had a very thin coat.

sentence: Justin always played funny jokes on Leslie at high school because OPTIONS:
- Justin was a prankster.
- Leslie was a prankster.
complete:
Justin was a prankster.