One Saturday, Lacey Was Sitting at Home When the Telephone

One Saturday, Lacey was sitting at home when the telephone rang. A local company was making promotional calls and told Lacey she had just won a $1000 gift certificate. She felt a rush of excitement at the thought of what she could do with $1000. Now Lacey finds that whenever she hears a telephone ring, she feels a surge of excitement. In this example, the rush of excitement that Lacey felt when she heard she had won the gift certificate is

A) the conditioned stimulus.
B) the unconditioned stimulus.
C) the unconditioned response.
D) the conditioned response.