Which psychological approach contends that psychology must study internal mental events in order to fully understand behaviour

A)  cognitive psychology 
B)  clinical psychology 
C)  developmental psychology 
D)  behaviourism

Cognitive Psychology

The branch of psychology focusing on mental processes such as perception, memory, thought, and problem-solving, and how they may affect behavior.

Internal Mental Events

Psychological occurrences within the mind such as thoughts, feelings, and memories that are not observable by others.

Behaviourism

A branch of psychology focused on studying and modifying observable behaviors.