Answer:
a. Sigmund Freud.
Step-by-step explanation:
Sigmund Freud was one of the famous psychologists who has developed the psychoanalytic theory of personality during the 19th century.
In his theory of psychoanalysis, Sigmund Freud argued that an individuals' behavior is described as the outcome of the interaction between three different dimensions of the mind, i.e, the id, ego, and superego.
His theory mainly focuses on the concept of the unconscious mind instead of a conscious mind. He believed any behavior or conflict that has occurred in an individual's life is the result of childhood experience.
In the question above, Dr Stroetz's bookshelves contain a large number of books written by Sigmund Freud.