Question 5 Dr. Frederic is studying whether immune suppression can be learned through classical conditioning. In her experiment rats are injected with a drug that suppresses the immune system and are simultaneously given an unusual-tasting liquid to drink. One week later the rats are again given the unusual-tasting liquid, and their antibodies are measured to see if the immune system was supressed. What is the CS in this experiment? Question 5 options:

a. the immune-suppressing drug

b. the unusual-tasting liquid

c. the suppression of the immune system

d. the lack of change in the immune system