Dr. King repeats the word tension to support how he views the word tension as positive and growth-producing.
In the passage Dr. King says that his is "not afraid of the word 'tension'." This makes option A an incorrect statement. Also, since he's addressing the use of the word tension in his speech, it's obviously intentional so option C is incorrect as well. Option B is wrong because Dr. King says that it helps "men rise from the dark depths of prejudice and racism". He believes that tension helps to point out "half truths" and allow people the chance to evaluate the issues.