Researchers paired rats’ drinking of saccharin-sweetened water with injections of a drug that weakened the immune system. after repeated pairings, sweetened water triggered the rats’ immune systems to break down. what was the conditioned stimulus in the study?

The conditioned stimulus is the sweetened water.

Explanation:

Classical conditioning is the process by which a behavior is acquired through various stimulus which provide responses.

Let's define which is which in this example:

Unconditioned stimulus (UCS): the drug injected into the rat's body to weaken its immune system. Unconditioned response (UCR): the weakening of the immune system. Neutral stimulus (NS): the saccharin- sweetened water, which by itself generates no response. Once the UCS and NS are combined, they generate the UCR; the weakening of the rat's immune system. Finally, the conditioned stimulus (CS) becomes the sweetened water, which without the drug (UCS) generates the conditioned response of the weakening of the immune system.

Ithink the answer is d.