Most people think of a person lying on the couch reflecting on memories to a doctor when they think of psychology. In fact, psychology is the scientific study of the mind and behavior. Although psychology was studied as a philosophical subject in ancient civilizations, it began to be studied experimentally in nineteenth-century Germany. German physician Wilhelm Wundt established the first psychology laboratory in 1879. It was Sigmund Freud, the Austrian physician, who made psychology widely popular. However, psychology is more complex than that and includes many branches. Biological psychology is focused on the study of the biological reasons for human or animal actions. Similarly, clinical psychology is concerned with the treatment of diseases or problems of the mind. While cognitive psychology is about the mental processes or thoughts, behavioral psychology is mostly about the study of behavior. Another interesting branch of psychology is the comparative one: it is mostly limited to the study of animal behavior and mental life. Developmental psychology seeks to understand how people change their behavior as they age. Another important branch is social psychology as it studies human beings in social situations. There are many branches of psychology that study specific fields such as sports, industrial, and educational psychology. Researchers have spent a lot of time studying the mind and behavior of people and animals.

How does the organizational structure of this passage support the author's purpose? A. It shows how psychology is in fact complex.
B. It classifies the mental processes of animals.
C. It compares psychology with other sciences.
D. It defines the idea of a psychologist by examples.