According to Cognitive Dissonance Theory, Which of the Following People

According to cognitive dissonance theory, which of the following people is most likely to change his attitude?

A) Joe, who is a political conservative but who argues in favor of liberal policies as part of a class assignment.
B) Sam, who is paid $100 to tell people how interesting a particular experiment is.
C) Ben, who makes his living telling people why satellite is better than cable.
D) Frank, who actually opposes unions, but makes up a pro-union argument just to annoy his parents.