Answer: Psychopathology.
Step-by-step explanation:
The branch of psychology concerned with the study of abnormal behavior and psychological dysfunction is psychopathology. Its definition is "the study of abnormal behavior and psychological dysfunction" which aligns exactly with what this question is asking us.
Psychopathologists explore how factors such as genetics, biology, environment, and individual experiences contribute to the development of abnormal behaviors, thoughts, and emotions. They study mental illnesses and what contributions these may have to the resulting condition.