Answer:
d. unconditioned response.
Explanation:
Unconditioned response: In psychology, the term "unconditioned response" in one of the parts in the theory of classical conditioning which was given by one of the most influential behaviorists and psychologists named Ivan Pavlov.
An unconditioned response is considered as an "unlearned response" that tends to occur instinctively in response to an unconditioned stimulus
Example: A dog who is being presented with food tends to salivate automatically. Here, food's smell is considered as the "unconditioned stimulus" and salivating is the "unconditioned response".
In the question above, the given statement signifies the unconditioned response.