The correct answer to this open question is the following.
Although there are no options attached we can say the following.
Terrance often worries. He is worried he won't pass the rigorous swim tests to become a lifeguard. He is thinking so deeply about this that he cannot think clearly in class and keeps missing the conversations his friends are having around him. This compulsive fretting is referred to as "rumination."
In psychological terms, Rumination can be understood as obsessive thinking that occupies the mind of an individual to the degree he forgets what is going around him. We can say he disconnects from reality because he is so deeply immersed in this obsessive thinking about some things that worry him.
This is not healthy and many times takes the individual into frustration and desperation. In severe cases, to depression.