Researchers condition a flatworm to contract when exposed to light by repeatedly pairing the light with electric shock.The electric shock is a(n)

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

Unconditioned Stimulus

In classical conditioning, a stimulus that naturally and automatically triggers a response without the need for prior learning.

Neutral Stimulus

An initially neutral stimulus that does not provoke an inherent response until it becomes linked with a naturally occurring stimulus.

Conditioned Response

A learned response to a previously neutral stimulus that has been repeatedly presented along with an unconditioned stimulus.