How were sit-ins a productive way to protest?

These groups became the grassroots organizers of future sit-ins at lunch counters, wade-ins at segregated swimming pools, and pray-ins at white-only churches. By sitting in protest at an all-white lunch counter in Greensboro, North Carolina, four college students sparked national interest in the push for civil rights.

(for the movement)

the answer is a. laws were enacted in the aftermath of the plot to make it harder to free slaves,increasing sectionalism