Final answer:
(C) John P. Grey was influential in improving mental health hospital conditions and removing restraints, while Sigmund Freud's psychoanalytic theory and ideas about the unconscious mind encouraged the new morality of the 1920s.
Step-by-step explanation:
The individual known for being influential in removing restraints and chains and implementing positive psychological interventions was John P. Grey. He was a psychiatrist in the 19th century who significantly improved the conditions of mental health hospitals and was against the use of mechanical restraints on patients.
Meanwhile, the psychologist whose ideas encouraged the new morality of the 1920s was Sigmund Freud. Freud was an Austrian neurologist who developed psychoanalytic theory, emphasizing the importance of the unconscious mind and early childhood experiences in shaping behavior.
His ideas influenced various aspects of culture, including modern therapy, and contributed to changing attitudes about human behavior and sexuality during the 1920s.