The correct answer among all the other choices is An unbiased attitude. If activists want people to understand their main idea, their messages need to be characterized by this. Thank you for posting your question. I hope this answer helped you. Let me know if you need more help.
Although both A and C makes sense, on the test I took that have this question, the correct answer is C. A clear claim, hope it helps for those who are struggling to choose between the answers :>
