Under the theories of learning, after a comparative and deep analysis of Edward Thorndike's 'Connectionism', Ivan Pavlov's 'Classical Conditioning', and B.F. Skinner's 'Operant Conditioning', which of the following statements most accurately clarifies the ontological difference in the stimulus-response (S-R) relationships and their control mechanisms across these three theories?

Among behaviorist learning theories, Thorndike's connectionism emphasizes the formation of S-R (Stimulus-Response) bonds based on satisfying outcomes under the 'Law of Effect'. Ivan Pavlov's classical conditioning is primarily related to involuntary, natural responses (such as salivation) where a natural stimulus is paired with a neutral stimulus (also called S-S conditioning). In contrast, B.F. Skinner's operant conditioning focuses on voluntary and active behaviors, where the organism responds first, and the resulting reinforcement determines the frequency of the behavior, understood as R-S conditioning.