Jamal is a clinician who’s providing medication therapy to a patient. Of the four types mental health professionals listed here, Jamal is most likely the psychiatrist. Psychiatrists are medical doctors who diagnose and treat mental illness through a biomedical lens, taking into account the patient’s physical health. As medical doctors, psychiatrists can prescribe medications and other treatments without restriction.
Aimee has a rather broad job description, but the fact that she works with registered nurses in a supportive role strongly suggests that Aimee is the psychiatric technician.
Zhang provides and leads therapeutic counseling sessions, which is, again, a broad job description. Certainly, this would be something a therapist does. Without further information and using the process of elimination, it is most likely that Zhang is the therapist.
Gayle has a research doctorate in psychology, and we are told that she conducts academic research. From the fact that she has a Ph.D. in psychology alone, we could say that she’s the psychologist. While there are psychologists who do treat patients, psychologists generally do not (and in most jurisdictions, are not allowed to) use medication therapy. In any case, it’s a safe bet to say that Gayle is the psychologist.