Final answer:
The conditioned response (CR) is learned through association during classical conditioning and diminishes through extinction methods, while the unconditioned response (UR) is a natural reaction that persists even after extinction of the CR.
Step-by-step explanation:
A key difference between the conditioned response (CR) and unconditioned response (UR) is that the CR occurs after a stimulus has been associated with an unconditioned stimulus through classical conditioning, while the UR occurs naturally in response to an unconditioned stimulus, without prior learning. The most accurate statement from the given options is 2) With the exception of spontaneous recovery, the conditioned response no longer occurs after treatment with extinction methods, whereas the unconditioned response remains.
This difference is evident in the example of Pavlov's experiments with dogs. At first, the dogs' salivation was an unconditioned response to the unconditioned stimulus of food. Through conditioning, when the bell (a conditioned stimulus) was rung in association with presenting food, it eventually elicited the conditioned response of salivation. However, when the bell was rung without the subsequent presentation of food (during extinction), the conditioned response of salivation diminished and could eventually disappear, whereas the natural salivation response to the food (unconditioned response) remained unchanged.