Although Cognitive Dissonance Is a Very Powerful Way to Change

Multiple Choice

Although cognitive dissonance is a very powerful way to change someone's attitude, it is not implemented on mass scales.Why not?

A) Most people are resistant to persuasion attempts.
B) Very few people ever experience cognitive dissonance.
C) People would become psychologically reactive to the persuasion attempt and do the opposite.
D) It would be difficult to create a situation of low external justification on a mass scale.