An 11-Year-Old Girl with an Overactive Immune System That Attacks

An 11-year-old girl with an overactive immune system that attacks her own body receives a treatment in which cod liver oil is paired with an immune-suppressant drug. After these initial trials, she occasionally receives only cod liver oil (without the drug) , yet her body still shows the desired impairment of functioning. According to the
Principles of classical conditioning, the immune suppressant drug would be considered the:

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