Story needs to be completed:
So 
OPTIONS:
- Patricia wanted to keep their diet because Patricia wanted to lose weight while Samantha was fine.
- Samantha wanted to keep their diet because Patricia wanted to lose weight while Samantha was fine.

My choice:
Samantha wanted to keep their diet because Patricia wanted to lose weight while Samantha was fine.
Problem: Continue the following story.

We returned the drill and opted to purchase a hammer, since the 
OPTIONS:
- drill was useless for our building project.
- hammer was useless for our building project.
Here's how I want to continue it: drill was useless for our building project.
Problem: James believes he could get the same number of grams  of stones with equal volume of oil but he was wrong because the 
OPTIONS:
- oil is lighter.
- stone is lighter.

My choice: oil is lighter.
[Q]: How does the sentence end?

Since Steven had an upset stomach and Craig was well, 
OPTIONS:
- Steven was brought some indigestion medicine.
- Craig was brought some indigestion medicine.

[A]: Steven was brought some indigestion medicine.
QUES: Continue writing.

Cooking the potatoes in the stew took less time than the broccoli because the 

OPTIONS:
- potatoes was unripe.
- broccoli was unripe.
+++++++++
ANS: broccoli was unripe.
QUES: Continue writing.

Putting on weight was the expected outcome for Matthew but not Nelson because 

OPTIONS:
- Matthew lost muscle mass.
- Nelson lost muscle mass.
+++++++++
ANS:
Nelson lost muscle mass.