Answer:
a) theories.
Explanation:
Sigmund Freud, Abraham Maslow, Erik Erikson, and Carl Rogers all developed ways to explain behaviors or events by offering ideas that organize observations. Their ideas are called theories.
Theories are established principles, below are some theories;
Sigmund Freud developed the psychoanalytic theory of personality development.
Abraham Maslow developed the hierarchy of needs theory
Erik Erikson promulgated the theory of psychosocial development.