How did the Non-Cooperation Movement become a mass movement?

Correct answer: Through the participation of many groups

The movement became a mass movement because participation extended beyond a small political leadership. Students, teachers, lawyers, traders, peasants, workers, and many ordinary people joined different forms of boycott and protest, although their local aims could vary. This broad social participation gave the movement national reach. Option A is correct; the other choices describe neither its membership nor its method.