Final answer:
Ivan Pavlov is most closely associated with classical conditioning, discovered through his famous experiments with dogs where they learned to associate the sound of a bell with food.
Step-by-step explanation:
The person most closely associated with classical conditioning is Ivan Pavlov. Pavlov's experiments with dogs, where he discovered that an unconditioned response like salivation could be triggered by a conditioned stimulus (such as a bell) when paired with the unconditioned stimulus (food), laid the foundation for this type of associative learning. This discovery is a key part of behaviorism and is often referred to as Pavlovian conditioning. In his experimental setup, Pavlov indeed presented food to dogs while simultaneously ringing a bell, leading the dogs to associate the bell with the presence of food. Eventually, the dogs would salivate at the sound of the bell alone, even when no food was presented. The correct answer to the initial question is, therefore, a. Ivan Pavlov.