While He Is in the Waiting Room at the Doctor's

While he is in the waiting room at the doctor's office,Arthur tries to classify infants' attachment based on their behavior.He is certain that the baby girl sitting across from him is securely attached because she

A) explores the unfamiliar room and the objects in it while staying in view of her mother.
B) stays very close to her mother for support.
C) is fearful of any strangers who come into the room.
D) is not distressed when her mother leaves the room.