Concept:Classical conditioning is a reflexive learning process where an unconditioned stimulus naturally triggers a response.
Explanation:In classical conditioning, an unconditioned stimulus (UCS) automatically produces an unconditioned response (UCR).
When a neutral stimulus is repeatedly paired with the UCS, it becomes a conditioned stimulus (CS) that evokes the conditioned response (CR).
This response occurs reflectively or automatically due to the learned association.
Option A correctly states that the conditioned response is forced reflectively by the unconditioned stimulus.
Option B is wrong because classical conditioning was discovered by Ivan Pavlov, not Skinner; Skinner is associated with operant conditioning.
Option C is wrong because reward dependent on response describes operant conditioning.
Option D is wrong because reinforcement after a response also belongs to operant conditioning.
Thus, the defining feature of classical conditioning is the automatic, reflexive nature of the response triggered by the unconditioned stimulus.
Answer:Option A: The occurrence of conditioned response is forced reflectively by unconditioned stimulus.