In the Late 1800s,there Was an Emphasis on Biological Causes

In the late 1800s,there was an emphasis on biological causes of mental disorders,which ironically reduced interest in treatments for mental patients.Why did this happen?

A) because it was thought that hospital staff were not adequately trained to administer new treatments
B) because it was thought that patients would improve more rapidly if they were not hospitalized
C) because it was thought that mental illness due to brain pathology was incurable
D) because it was thought that physicians should devote more time to the physically ill