Answer:
d. CS + UCS; continuous
Step-by-step explanation:
Conditioned stimulus: In psychology, the term conditioned stimulus is defined as a formerly neutral stimulus that triggers or gives rise to a conditioned response after being connected with an unconditioned stimulus.
Unconditioned stimulus: In psychology, the term unconditioned stimulus refers to the stimulus that naturally, unconditionally, and automatically triggers a particular response.
Continuous schedule: In psychology, the term continuous schedule is a schedule of reinforcement and is also denoted as CRF. It occurs when a particular reinforcement is being given after the achievement of every single target behavior.