He spoke out and asked for civil, economic, and racial rights. It was one of the most unforgettable speech's in history. The main purpose was to fight for the rights of African Americans/Blacks. Martin incredibly ended racism using only his words instead of fighting.
Hope this helps! :)
Your answer is going to be B
"A" is probably the best choice. All of your other choices are close-ended questions, and can only be answered with a simple yes or no, But "A" is an open-ended question because the answer wont be just a "yes" or "no".
Hope this helps!
Big, bigger, or biggest! :D