In classical conditioning, the is an unlearned reaction to a given stimulus. for example, if you have an allergy to pollen and sneeze, sneezing is an unlearned reaction to the pollen (i. e., the stimulus).

a. conditioned response
b. conditioned stimulus
c. unconditioned response
d. unconditioned stimulus

c. unconditioned response

Explanation:

Unconditioned response: In psychology, the term unconditioned response is a part of classical conditioning and is also denoted with UCR, and it was given by Ivan Pavlov.

The unconditioned response is referred to an unconnected response that generally occurs in response to an unconditioned stimulus or UCS naturally.

Example: If an individual feels hungry and smells the food then in this scenario, the smell of food is unconditioned response whereas the hunger feeling is an unconditioned stimulus.

In the question above, the statement signifies the unconditioned response.