Final answer:
The neutral stimulus that became the conditioned stimulus in the example of the student's cat Friday is the alarm. The alarm was originally neutral but after being paired with a reinforcing event, it elicited the conditioned response of meowing.
Step-by-step explanation:
In the example of the student's cat Friday, the neutral stimulus that became the conditioned stimulus is b) The alarm. Initially, the alarm did not elicit any response from Friday, but after being repeatedly paired with something that draws a natural response (such as being fed in the morning), the alarm alone started to elicit the conditioned response which is meowing.
Similarly, in the classical conditioning example of Pavlov's dogs, the tone (neutral stimulus) which initially had no effect on the dogs, after being paired with the unconditioned stimulus (meat powder), eventually caused the conditioned response (salivation) when the tone was sounded. The tone thus became the conditioned stimulus. Extinction of the conditioned response occurs when the conditioned stimulus is no longer followed by the unconditioned stimulus, over time weakening the association.