Adam remembered the advertising for John Deere lawn tractors because in one ad the person driving the tractor was a female wearing an attractive bikini, in another it was of a mother with two kids playing in a yard, and in a third of a man in a

business suit. In this example, Adams' recall of the ad and encoding of the John Deere name into his cognitive map was enhanced by the concept of:
A) identifiable selling point
B) campaign duration
C) variability theory
D) source credibility

C