You Conduct a Single-Subject Experiment to See Whether You Can

You conduct a single-subject experiment to see whether you can reduce disruptive behavior in a third-grader, Jonathon, by ignoring instances when he talks out of turn. You first observe his behavior under normal conditions, and then after his teacher has been instructed to ignore him when he talks out of turn. You find that his talking out of turn is reduced when it is ignored. In this scenario, _____.

A) you can safely conclude that your treatment was the only variable that affected Jonathon's urge to talk out of turn
B) you can conclude that the effect of your treatment is only temporary
C) you cannot safely conclude that your treatment changed his behavior because your treatment is confounded with time
D) None of the answers is correct.