Final answer:
Psychopathology refers to the study of mental disorders and includes all unusual behaviors, signs, and symptoms that signify mental distress or dysfunction.
Step-by-step explanation:
Psychopathology is a term in psychology that pertains to the scientific study of mental disorders, including efforts to understand their genetic, biological, psychological, and social causes; engage in the classification of disorders; study the course of pathological behaviors, experiences, and symptoms; and develop treatments to ameliorate the suffering caused by mental disorders. Psychopathology does not simply refer to a set of behaviors, signs, or symptoms that are unusual; rather, it refers to a set of behaviors, emotions, and cognitions in an individual that are deeply distressing, dysfunctional, or deviant, and that fall outside the range of normal functioning or cultural norms.
Psychopathology involves the assessment of how these factors impair an individual's ability to function in everyday life, and can be seen within various branches of psychology such as clinical psychology, counseling psychology, and developmental psychology. Therefore, the definition of psychopathology encompasses option 4): All of the above - a set of behaviors, signs, and symptoms that are unusual and indicative of a mental disorder or distress.