Answer:
Step 2 - presentation of the neutral stimulus.
Explanation:
Classical conditioning is the learning procedure in which the active stimulus when mixed with neutral stimulus elicit a strong response. This conditioning was explained by Pavlov.
In the given situation, the tone acts as the neutral stimulus. This stimulus will combine with the puffing that acts as the other strong stimulus and result in the blinking of the animals. Here, Mark shows the step 2 of the classical conditioning.
Thus, the answer is step 2 - presentation of the neutral stimulus.