Answer:
Psychobiology
Step-by-step explanation:
Psychobiology is the science that focuses on studying the psychology of individuals based on their biological functions. In other words it deals with the interactions between biology (neurological system, neurotransmitters) and their effects on the individual behavior.
Therefore, an individual working in psychobiology might study the effects of drugs (biological) or try to explain behavior based on chemical activities in the nervous system (explaining behavior based on biology)