In an Experiment I Am Conducting, Rats Have to Learn

In an experiment I am conducting, rats have to learn that, when an odor is present, they must leave the vicinity in order to avoid being shocked. If I lesion a certain part of the brain the rats will not be able to learn the task because their emotions will not be able to guide their behavior. Which part of the brain should I lesion to get this effect?

A) hypothalamus
B) limbic system
C) cortex
D) amygdala