I believe the correct answer is the last one - to provide a contrast to his group's nonviolent efforts.
Martin Luther King advocated protests, but those which didn't end up in violence. He wanted to fight for equal black rights, without having to resort to aggression and crime. Thus he added these sentence to distinguish his group from those such as Black Panther Party, and others.
I think the answer is B! That’s really nice of you, you don’t have to I’m just here to help lol!
Observations because the others should be in your body paragraphs and the thesis is the response to the task i.e your stance on a topic,issue or claim