In my opinion, the correct answer is C. anger. This phrase doesn't give the audience a reason to panic or despair, and it is far too strong to cause mere anticipation. It causes downright anger because, according to the speaker, the injustice continues in spite of all the efforts. This is an appeal to ethos, a very delicate matter that is supposed to engage the listeners, rather than just move them emotionally.
C, this is because it talks about the different chemicals in the air which can cause cancer. The other answers are vague statements about other things, not poisonous dust.
