The Book's Authors Point Out That One Reason Clinical Approaches

The book's authors point out that one reason clinical approaches tend to be self-contained, and even myopic, is that

A) clinicians need to have only one focus because there is so much to pay attention to.
B) as new models emerge, they often define themselves as distinct from older models.
C) it is essential to narrow the vast range of variables one pays attention to in order to provide the best service to clients.
D) all of the above