Final answer:
Your roommate is taking a class in Social Psychology.
Correct option is d.
Step-by-step explanation:
The subject your roommate is taking a class in is Social Psychology. Social psychology is a subfield of psychology that studies how people's thoughts, feelings, and behaviors are influenced by social interactions and situations.
In the experiment she was reading about, researchers investigated the cues people give when they really like someone, which is a topic within social psychology.