If you were writing a brief profile of rosa parks explaining why you admire her, which of the following sentences would make a good thesis statement?

a. in 1995, rose park refused to give up her seat on a bus.
b. rosa park's refusal to give up the seat sparked the montgomery bus boycott.
c. many people believe that rosa parks was a great women.
d. rosa park showed the the country how one act of courage can make a difference.