The correct answer is Depression
Depression is a highly prevalent mental illness and is the most associated with s/de. It tends to be chronic and recurrent, especially when untreated.
The treatment is medicated and psychotherapeutic. The choice of antidepressant is based on the subtype of depression, personal and family history, good response to a particular class of antidepressants already used, the presence of clinical disease and the characteristics of antidepressants.