An Advertisement for AT&T Long Distance Telephone Service Split the Screen

An advertisement for AT&T long distance telephone service split the screen in two and showed a person on each screen talking on the telephone. Below each person, there was a running total of the cost of the call. At the end of the commercial, the total cost on the AT&T side was lower than that for the Sprint side. This is an example of which type of ad?

A) one-sided message
B) two-sided message
C) fear appeal
D) third-party endorsement
E) comparative ad