Kate is consistently anxious because she is always thinking about the dangers of slipping and falling. whenever he leaves his apartment, charlie immediately goes back at least 10 times to check that the door is locked. kate's thoughts best illustrate a(n) and charlie's behavior best illustrates a(n)

Obsession; compulsion

Explanation:

Obsession: The term obsession is defined as a mental illness or disorder in which an individual experience repeated and unwanted feelings, images, thoughts, or sensations.

Compulsion: The term compulsion is defined as rule-based behavior that an individual should perform a specific task to make oneself feel better and normal and avoid negative consequences.

In the question above, Kate's thoughts beat illustrate a(n) obsession, and Charlie's behavior best illustrates a(n) compulsion.