Two Groups in Lincoln, Nebraska Held Rallies About Health Care

Two groups in Lincoln, Nebraska held rallies about health care during the summer of 2009, one supporting and one opposing legislation proposed to overhaul America's health-care system. At one point, the two groups went beyond holding signs and shouting slogans, and tempers flared. Objects were thrown, shoving occurred, and the police had to step in to break up the

A) social movement.
B) riot.
C) rally.
D) march.