Final answer:
The incorrect statement is (d), as acknowledging the history of stereotypes in humor is crucial for preventing future prejudice, rather than acting as a justification for their existence.
Step-by-step explanation:
The statement that is NOT true among the options provided is (d) "Stereotypes in humor were part of our history, so it would not be good to pretend it never happened." This statement suggests that acknowledging the historical presence of stereotypes in humor excuses or justifies their existence, when in fact, recognizing and understanding these past stereotypes is important for learning and preventing further prejudice and discrimination. The other statements (a) Research shows that stereotypical humor causes prejudice, (b) Stereotypical images were used by both sides during WWII, and (c) Minorities, women, ethnic groups, and religions have been stereotyped through humor are accurate and reflect historical and social research findings.