16) In this passage Dr. King cautions his audience against using violence by telling them to A) stand on the warm threshold leading to the palace of justice. B) distrust all white people except those participating in the march. C) conduct their struggle on the high plane of dignity and discipline. D) shake the foundations of their nation until the bright day of justice emerges.

Since the passage is not included with the question. We can understand that a request against using violence cannot include some offensive action words, such as "distrust"; "stand"; "shake", which were used in the sentences A, B and D. But the meaning of his request is clearly perceived in the sentence C, that, despite of being a strugle, it should be conducted on what he considered a high plane of dignity and discipline.

Answer C.