What scientific discipline combines biology and psychology to understand the biological bases of behavior?

The correct choice is psychobiology, which is a scientific discipline that merges concepts from both biology and psychology to explore how biological processes influence behavior and mental states. This field emphasizes understanding how the brain, neurotransmitters, hormones, and genetic factors contribute to behavioral patterns and psychological phenomena.

Neuroscience, while closely related, focuses more specifically on the nervous system, particularly the brain's structure and function at a cellular and molecular level. It often delves into the neurobiological aspects of behavior but does not encompass the broader psychological implications as fully as psychobiology does.

Behavioral science primarily examines behavior in a social context, emphasizing observable actions rather than the underlying biological mechanisms. Cognitive psychology studies mental processes such as perception, memory, and decision-making without necessarily linking them to biological factors.

Cognitive psychology investigates how people think and process information but does not integrate the biological basis of those cognitive functions in the same way that psychobiology does. Thus, psychobiology distinctly represents the intersection of biology and psychology, making it the most suitable answer.