Problem: How does the sentence end?

Brett is often anxious and  under much stress at work, Samuel has a calm personality. 
OPTIONS:
- Brett constantly worries.
- Samuel constantly worries.
Answer: Brett constantly worries.

Problem: How does the sentence end?

Fashion was not Katrina 's strength, while Laura was an expert, so 
OPTIONS:
- Katrina asked her which dress was right for the occasion.
- Laura asked her which dress was right for the occasion.
Answer: Katrina asked her which dress was right for the occasion.

Problem: How does the sentence end?

All the routine tasks at work bores Donald but Ryan is fine with it, 
OPTIONS:
- Donald prefers variety in work.
- Ryan prefers variety in work.
Answer: Donald prefers variety in work.

Problem: How does the sentence end?

Kyle received a fantastic education from his teachers thanks in no small part to Ian, for whose benefit 
OPTIONS:
- Kyle provided proper guidance.
- Ian provided proper guidance.
Answer:
Ian provided proper guidance.