The words in bold in the given passage exemplify the use of Pathos. Here option C is correct.
Pathos is an appeal to the audience's emotions, and in this case, the speaker is expressing a strong emotional plea for a more forceful and passionate response to the issues at hand.
The use of terms like "fiery stream," "biting ridicule," "blasting reproach," "withering sarcasm," and "stern rebuke" evoke a sense of intense emotion and urgency. The speaker is calling for a response that goes beyond logical argumentation (logos) or appeals to credibility and authority (ethos).
Instead, they are emphasizing the need for an emotional and visceral reaction, a stirring of the nation's feelings and conscience to address the perceived moral and societal issues. Here option C is correct.