Dr. Gerschivin is a psychologist that teaches people how to relieve pain,

cope with chronic illnesses, and to perform self-screenings to prevent diseases, such as cancer. Dr. Gerschivin is working in the field of

a. medical psychology.

b. behavioral medicine.

c. homeopathic psychology.

d. developmental medicine.

a. medical psychology.

Explanation:

Medical psychology: The term medical psychology refers to the process of applying psychological principles to practice or wok on medicine. The medical psychology field is fairly comprehensive instead of primarily drug-oriented, in case of both mental and physical disorders.

The medical psychology branch focuses on the client's emotional and mental state or reaction to a specific illness and the recovery process from an illness.

In the question above, Dr Gerschivin is working in the field of medical psychology.