Marie enters the playroom of the psychology lab with her one-year-old son Aaron. Aaron ignores the many attractive toys in the room and clings to his mother. When Marie leaves the room, Aaron begins to cry hysterically. When his mother returns and tries to comfort him, Aaron cries harder, kicks, and resists her efforts to hold him. Aaron would most likely be classified as: a. difficult and slow-to-warm-up. b. insecurely attached. c. low-reactive. d. securely attached.