Alfredo brings his lucky pencil with him for his exams. His pencil was accidentally paired with a good grade on his exams. Alfredo's behavior is an example of a:

Nature is to ____ as nurture is to ____

a. conditioning; learning b. learning; conditioning c. environment; genetics d. genetics; environment

In Pavlov's experiments with dogs, the unconditioned stimulus was the

a. food. b. bell. c. salivation to the food. d. salivation to the bell.