According to the Informational View of Learning, Why Is the Response

According to the informational view of learning, why is the response to the unconditioned stimulus (US) in classical conditioning eventually made to the conditioned stimulus (CS) ?

A) because an organism comes to expect the unconditioned stimulus (US) when the conditioned stimulus (CS) is present
B) because an organism cannot discriminate the conditioned stimulus (CS) from the unconditioned stimulus (US)
C) because the conditioned stimulus (CS) initiates an automatic association between the conditioned stimulus (CS) and unconditioned stimulus (US)
D) because the organism cannot discriminate between the conditioned stimulus (CS) and unconditioned stimulus (US)