Problem: How does the sentence end?

Laura offered her condolences to her friend Patricia at her mother's funeral. 
OPTIONS:
- Laura was upset by her loss.
- Patricia was upset by her loss.
Answer: Patricia was upset by her loss.
sentence: Emily volunteers at the local shelter every weekend unlike Sarah, because  OPTIONS:
- Emily has a soft heart.
- Sarah has a soft heart.
complete: Emily has a soft heart.
Katrina made her halloween costume for the party, but Rachel bought hers. 
OPTIONS:
- Katrina is rich.
- Rachel is rich.
Rachel is rich.
Input: Continue writing.

The engineer had to take the pressure off of the box from the ball because the 
OPTIONS:
- box was too heavy.
- ball was too heavy.

Continued: ball was too heavy.
Story needs to be completed:
The couple agreed that marriage was a better idea than engagement, because the 
OPTIONS:
- marriage was more stable.
- engagement was more stable.

My choice:
marriage was more stable.
Problem: How does the sentence end?

I'm joining a gym to improve my strength and stamina. Running on treadmill should be good for the 
OPTIONS:
- stamina .
- strength .
Answer:
stamina .