When Ivan Pavlov trained a dog to salivate and expect food whenever it heard a bell, he demonstrated the existence of classical conditioning. This process uses an initially neutral stimulus (a bell ringing) paired with an innate or biological stimulus (food) to elicit an innate response (salivation). Eventually, the biological stimulus can be removed and the neutral conditioned stimulus will result in the same response, despite the absence of the biological stimulus.

Extinction happens when you present the conditioned stimulus without the unconditioned stimulus, thus unpairing the two stimuli. The conditioned response will happen less frequently following the extinction phase.

Ivan Pavlov conducted experiments on dogs, in which he used classical conditioning principles to spur the dogs to salivate whenever a bell was rung. Specifically, the dogs learned to associate the ringing of the bell (the conditioned stimulus) with the presentation of food (the unconditioned stimulus). 

"Classical conditioning involves pairing a neutral stimulus with a non-neutral one until there is a nonneutral reaction to the neutral stimulus, whereas operant conditioning occurs when a creature's actions are influenced by the consequences of their actions" is the only answer choice that correctly lists the definitions of the two types of conditioning.

Extinction is the eventual cessation of a learned response (salivating) after the conditioned response (the bell) and unconditioned (the food) are no longer presented together to the subject (the dog).

"A dog begins salivating to the sound of a bell after the bell and food have not been presented together for a significant period of time" is the opposite of the classical conditioning concept of extinction, and goes against the rules of classical conditioning. 

"A dog starts salivating to the sound of a bell because the bell and food are presented together" refers to acquisition, the learning of the conditioned stimulus and the unconditioned stimulus pairing. 

"A dog salivates to the presentation of a red napkin because the red napkin was often presented with a bell, which was originally often presented with food" describes second-order conditioning, in which a conditioned stimulus from a previous round of conditioning becomes the unconditioned stimulus in a new round. 

"A dog salivates to the sound of a whistle because the bell and food were presented together many times, and a whistle is similar to a bell" refers to the concept of generalization, when the conditioned response is observed even when the conditioned stimulus is slightly different from the original one. 

In Pavlov's dog experiment, there were 5 elements:

Unconditioned Stimulus- The food that triggered the dog's drooling.

Unconditioned Response- The drooling due to the presence of food.

Neutral stimulus- a stimulus that initially does not produce the drooling

Conditioned Stimulus- The ringing of the bellby the dog's owner.

Conditioned Response- The drooling due to the sound of the bell.

The most correct answer is: The dog drools due to the sound of the bell. 

Given that this question focuses on the effects on the dog, salivation may be considered a response. Because salivation is said to occur whenever food is present, this would be an unconditioned response because no learning was required in the process. Conversely, the food in this instance would be an unconditioned stimulus. 

Because the problem specifies that the dog salivates every time it sees the food, this would mean that no learning was part of the response, making salivation an unconditioned response. Because the food is causing the response, it is a stimulus. Furthermore, because the response is unconditioned, the stimulus is unconditional as well. 

Because the question does not ask about the effects on the dog, we can deduce that the tones were stimuli. Given that these stimuli elicited no response from the dogs, they can be initially labeled as neutral stimuli because there is no learned association with food at this time. 

In Pavlov's experiment, he coupled what was once a neutral stimulus with an association (food) for the dogs. This neutral stimulus became associated with food through a learned process, thus becoming a conditioned stimulus for what was once an unconditioned response.