[Q]: How does the sentence end?

Having outgrown diapers, the child switched to shorts but not pants, as the 
OPTIONS:
- shorts fit perfectly.
- pants fit perfectly.

[A]: shorts fit perfectly.
QUES: Continue writing.

Ian began to test Ryan on various elements in the periodic table, because 

OPTIONS:
- Ian was good at science.
- Ryan was good at science.
+++++++++
ANS: Ian was good at science.
Problem: How does the sentence end?

Randy was capable of performing the surgery but Brett was not because 
OPTIONS:
- Randy had done it many times before.
- Brett had done it many times before.
Answer: Randy had done it many times before.
sentence: My cavities were not as painful as my broken fingers because the  OPTIONS:
- cavities healed quick.
- fingers healed quick.
complete: cavities healed quick.
He knew that the sun was closer to earth than the other star, because the 
OPTIONS:
- sun was brighter.
- star was brighter.
sun was brighter.
Problem: Continue the following story.

Rebecca taught Samantha about mushroom picking because 
OPTIONS:
- Rebecca was knowledgeable about which ones were edible.
- Samantha was knowledgeable about which ones were edible.
Here's how I want to continue it:
Rebecca was knowledgeable about which ones were edible.