Final answer:
Among the given options, the example of classical conditioning is a person being afraid of thunder and lightning due to previous experiences with tornadoes. This example shows the association between a natural reaction to an unconditioned stimulus and a conditioned stimulus developed through repeated paired exposure.
Step-by-step explanation:
An example of classical conditioning among the provided options is a) being afraid of thunder and lightning because the last two times you were in a thunderstorm, there were also tornadoes. This scenario demonstrates classical conditioning as it shows how a natural reaction (fear) to an unconditioned stimulus (tornadoes) gets associated with another stimulus (thunder and lightning) after repeated occurrences.
The key components here are as follows: the Unconditioned Stimulus (UCS) is the tornado; the Unconditioned Response (UCR) is the initial fear response to the tornado; the Conditioned Stimulus (CS) becomes the thunder and lightning; and the Conditioned Response (CR) is the fear that now arises upon experiencing the thunder and lightning.
In contrast, option d) regarding rewarding students with a pizza party corresponds to operant conditioning, where behaviors are modified through consequences such as rewards or punishments.