Problem: Megan was a real headache for Elena, because

My choice: Elena was always cleaning up all kinds of trouble.

Problem: Michael was able to get the stains out of the sofa, unlike Hunter, because

My choice: Michael used a professional service.

Problem: There were more fish in the aquarium than in the fish tank because the

My choice: tank was narrower.

Problem: Alex wanted to swim in the ocean instead of the lake because the

My choice:
ocean is easier to float with its saltwater property.