Problem: How does the sentence end?

Nelson had lots of new ideas, but not Robert because 
OPTIONS:
- Nelson was not very original in thought.
- Robert was not very original in thought.
Answer: Robert was not very original in thought.

Problem: How does the sentence end?

Joel spends a lot more time sitting down than Donald because 
OPTIONS:
- Joel works in an office.
- Donald works in an office.
Answer: Joel works in an office.

Problem: How does the sentence end?

At the gym, Kevin followed Derrick 's lead during the exercise routine. 
OPTIONS:
- Kevin was his student.
- Derrick was his student.
Answer: Kevin was his student.

Problem: How does the sentence end?

I'm getting a dog as a pet and I'm going to buy it a bowl before a leash because the 
OPTIONS:
- bowl is more useful.
- leash is more useful.
Answer:
bowl is more useful.