Skinner conducted a famous study in which he punished bar pressing in rats attempting to obtain food by having the bar slap their paws each time they pressed it. Based on the results of this study, Skinner concluded that punishment is ineffective in the long run. A more accurate conclusion would be

A) punishment becomes more effective with the passage of time.
B) punishment is effective in the long run if it inflicts enough pain.
C) punishment does not weaken a response when no other response is available.
D) negative reinforcement is ineffective in the long run, but punishment is very effective.

Skinner's study actually showed that punishment reduced the frequency of the targeted behavior in the short term, but as soon as the punishment was removed, the rats resumed pressing the bar. However, when an alternative response was available (such as pressing a different bar), the rats were less likely to return to the punished behavior. Therefore, punishment may not be completely ineffective in the long run, but its effectiveness is limited and dependent on the availability of alternative behaviors. Choice A and B are incorrect because Skinner did not find evidence to support these claims. Choice D is also incorrect because the statement is not related to Skinner's study and is not true in general.