Mr. Goldstein decides to give his students points, usable for extra free time, when they raise their hands and wait to be called on. He discovers that more students raise their hand and fewer students blurt out answers when he awards points than when he does not. This finding seems to show O a functional relation between points and hand raising. O punishment of blurting out answers. O points serving as a motivating operation for hand-raising. O points exerting stimulus control over blurting out answers.