Answer: Alex is most likely suffering from A. major depressive disorder.
Step-by-step explanation: People suffering from a major depressive disorder usually experience a feeling of sadness and a loss of interest in certain activities, including normal day-to-day activities such as going to school or work. It is highly difficult for a person with major depression to even get out of bed and socializing with members of his/her own family. Therefore, Alex, which experiences all of these symptoms, is most likely suffering from major depressive disorder as he spends most of his time in his bed, he has lost interest in school and he does not even socialize with his family.