Final answer:
In classical conditioning, a buzzer or tone starts as a neutral stimulus and becomes a conditioned stimulus once it is repeatedly paired with an unconditioned stimulus (like meat powder) and elicits the conditioned response of salivation.
Step-by-step explanation:
In a typical classical conditioning experiment by Ivan Pavlov, a buzzer or tone serves initially as a neutral stimulus, which is a stimulus that does not naturally elicit a response. When Pavlov repeatedly paired the tone with the unconditioned stimulus (meat powder), the tone eventually elicited salivation from the dogs on its own. Therefore, the correct answer is c. neutral stimulus which becomes a conditioned stimulus. The tone, originally a neutral stimulus, becomes a conditioned stimulus (CS) through repetitive association with the meat powder, which is the unconditioned stimulus (UCS). As a result of this process, the tone, now a conditioned stimulus, elicits the conditioned response (CR) of salivation, which was initially an unconditioned response (UCR) to the food.