Question

Dr. richards explained to his client that obsessive-compulsive disorder appears to be heavily influenced by biological causes. dr. richards is explaining the ________ of obsessive-compulsive disorder.

Answer 1

Dr. Richards explained to his client that obsessive-compulsive disorder appears to be heavily influenced by biological causes. Dr. Richards is explaining the etiology of obsessive-compulsive disorder.
Etiology refers to causes of something - in this case, the doctor is telling his client why his OCD came to be.

Answer 2

Dr. Richards is describing the cause of the disorder.