Problem: How does the sentence end?

The soldier tried to put the harness on the chest of the dummy but the 
OPTIONS:
- chest  was too small.
- harness  was too small.
Answer: harness  was too small.
sentence: Kyle filed the papers for his client, Leslie, because  OPTIONS:
- Kyle hired him as a disability attorney.
- Leslie hired him as a disability attorney.
complete: Leslie hired him as a disability attorney.
Brian decided that they were going to buy shares in a racehorse but Benjamin could not because 
OPTIONS:
- Brian was rich.
- Benjamin was rich.
Brian was rich.
Input: Continue writing.

Victoria could throw a bean bag further than Amy because 
OPTIONS:
- Victoria worked out and had a strong arm.
- Amy worked out and had a strong arm.

Continued: Victoria worked out and had a strong arm.
Story needs to be completed:
Elena kept laughing at Mary in a mean way whenever she started singing because 
OPTIONS:
- Elena thinks she can't sing.
- Mary thinks she can't sing.

My choice:
Elena thinks she can't sing.
Problem: How does the sentence end?

It was easier to sleep on the cot than the bed because the mattress on the 
OPTIONS:
- cot was hard.
- bed was hard.
Answer:
bed was hard.