Whenever Five-Year-Old Claire Goes to the Dentist,she Becomes Anxious and Cries.Since

Whenever five-year-old Claire goes to the dentist,she becomes anxious and cries.Since she was not afraid of the dentist on her first visit,her fear was a learned behavior.The UCS in this case was probably

A) the dentist's beard.
B) sweet toothpaste.
C) the pain associated with teeth cleaning.
D) the sound of the music in the dentist's waiting room.