John’s car radio tuner is broken. Only 2 stations can be obtained. One is JJJ: “Yeah, we got sum fresh new stuff comin’ ya way on your Friday morning...”. The other is a classic hits easy-listening station: “And now we have a double-play from Neil Sedaka....”. Both are tolerable in short bursts, but, by switching between stations when each gets bad, John is able to minimise his discomfort. What theoretical principle does this support? a. two factor theory of avoidance b. response alternation c. Guthrie's stop-action principle d. single factor theory of avoidance