Researchers have found that animals show evidence of classical conditioning if they are injected with a drug that chemically causes immunosuppression while they are simultaneously drinking an unusual-tasting liquid. in these studies, the conditioned response would be: a. the immunosuppression. b. the injection of the drug. c. the taste of the liquid that is used. d. fear of the injection process.

alternative D.

Explanation: The animals that go through this process understand that everytime they drink the unusual-tasting liquid they will be injected, being that a very unpleasant series of events. They are conditioned, therefore, to be afraid of the unpleasantness of this process by associating pain to the actions that are part of it.

exposure to hazardous carcinogens and toxic substances can cause breathing problems, such as copd and various types of cancer. it also increases the risk of heart attacks and strokes and has serious (but no less unattractive) side effects, such as aging, yellow teeth, a terrible smell and damage to the vocal cords.