In a Study by Robert Ader and Nicholas Cohen,some Rats

In a study by Robert Ader and Nicholas Cohen,some rats were taught to associate sweet-tasting saccharin with cyclophosphamide,a drug that weakens immune response.Later,when given only saccharin,how did the rats respond?

A) demonstrated an increased ability to manage stress.
B) showed an improved ability to heal small wounds on their skin.
C) demonstrated less accuracy on a previously mastered maze.
D) produced significantly fewer antibodies to foreign cells.