Answer:
Option c: Unconditioned stimulus ; conditioned stimulus
Step-by-step explanation:
Classical Conditioning
This is a form of stimulus that does not bring about a new behavior but rather it makes an existing behaviour to resurface or occur.
Unconditioned Stimulus
This is often referred to as a natural stimulus that is brought about due to a response without prior learning such as food in the dog's mouth.
Unconditioned Response
They are simply unlearned, reflexive response such as dog's salivation
Conditioned Stimulus
In this type of stimulus, it is said to be originally neutral but comes to ignite or elicit a reflexive response such as the sound of bell. The Conditioned Response in this case is is commonly defined as a Learned reflexive response to a said or previous neutral stimulus. E.g Dog's salivation to sound of bell.