Brittany Came to a Therapist Complaining That She Just Doesn't

Brittany came to a therapist complaining that she just doesn't enjoy life lately. She says that for the past couple of months, she finds she just doesn't feel like doing the things that she used to love to do. She has also lost a lot of weight and sleeps much more than usual but still feels tired all the time. She says she just can't concentrate on anything. However, she denies feeling sad. Brittany's most likely diagnosis is

A) dysthymic disorder.
B) bipolar II disorder.
C) major depressive disorder.
D) She has no disorder.