Which of the Following Experiments Is Least Likely to Be

Which of the following experiments is least likely to be recreated again today?

A) Skinner's experiment examining pigeon's behavioral responses to schedules of reinforcement
B) Ivan Pavlov's experiment examining dog's salivary responses
C) John Watson's experiment examining operational conditioning on a 9-month-old child
D) Edward Thorndike's puzzle box experiments examining cat learning patterns