The author says the Greensboro Four wore their Sunday best for the sit in. What do they mean by "Sunday best"? Why do you think the students wore their Sunday best that day?

"Sunday best" means the clothes that are usually worn for Sunday services (church) or the person's best clothes.

The students wore their best for the occasion of eating lunch at the restaurant.

Explanation:

"Greensboro sit-in" was an act of non-violent protest against the segregation in Greensboro restaurant. The protest was started by the students of North Carolina Agricultural and Technical State University. The University is situated in Greensboro. The four students who started this protest were Ezell Blair, Jr., Joseph McNeil, David Richmond, and Franklin McCain. On February 1, 1960 these students dressed their "Sunday Best". The author used "Sunday best" to exemplify that these students were wearing their best dress.

"Sunday Best" refers to the clothes of a person that are worn on special occasions or Church services.

The students wore their "Sunday Best" because they were going for the occasion of having lunch at the restaurant where African Americans were denied lunch. That day was a special occasion for these students as they were going that take their first step towards protesting against the segregation in restaurants.