Problem: Rachel is teaching Samantha how to read a book that is very interesting, since

My choice: Samantha is a student.

Problem: Felicia was going on a trip to Japan and asked Elena how to fit in because

My choice: Elena had previously traveled to Japan.

Problem: Ryan always preaches for more funding for the military, while Samuel supports the arts more.

My choice: Samuel is a liberal.

Problem: Red nail polish makes Tanya's nails looks nicer than Samantha's because

My choice:
Tanya likes to paint her nails.