Answer:
The correct answer is:
behaviorism
Step-by-step explanation:
Behaviorism, structuralism, and functionalism were the earliest schools of thought in the field of psychology, but neither of the last two (structuralism, and functionalism) remains today, both have influences on modern-day psychology. Structuralism played a role in the metamorphosis of psychology into an experimental science, while functionalism acted as a precursor for the development of behaviorism.
Behaviorism, also known as behavioral science is a theory of learning, which states that all behaviors are learned through interaction with the environment, through a process called conditioning, thus, behavior is simply a response to environmental stimuli. Behaviorism can also be further divided into two types: Methodological behaviorism and radical behaviorism.
Psychoanalysis is a newer school of thought compared to the other three.