You are watching a really scary movie. the main character is about to be attacked by a monster. you look over to the person sitting next to you and see fear in his face. what part of the limbic system allows you to evaluate this expression

I believe the answer is Amygdala

Amygdala is a part of our limbic system that is responsible to control all things that relevant for our fight or flight situation.

This includes several processes such as Evaluating emotion, processing memory, controlling quick decision-making process, et.