What was Bloody Sunday and what happened? (civil rights movement)

On "Bloody Sunday," March 7, 1965, some 600 civil rights marchers headed east out of Selma on U.S. Route 80. They got only as far as the Edmund Pettus Bridge six blocks away, where state and local lawmen attacked them with billy clubs and tear gas and drove them back into Selma.

answer; /// i believe that the correct answer is (divison of labor);