In Pavlov's procedure the dog's salivation is elicited by the bell whether or not the dog does anything. In Skinner's box the rat's food depends entirely on whether the rat presses the lever. Why does this difference in what controls the outcome matter more than the difference in species or apparatus?

D. Because one is learning what predicts, the other what an action produces.

One question separates them: does the animal's behaviour change what happens? Pavlov's dog could sit still and the food would still arrive; Skinner's rat determines its own outcome. It is about where the contingency lies rather than reflex versus voluntary, and the same organism does both kinds of learning constantly.