How did the Non-Cooperation Movement make national politics more mass-based?

Correct answer: Different groups got opportunities to participate in their own ways.

The movement became mass-based because participation was possible through many forms of action rather than only through formal political institutions. Students left government schools, lawyers gave up practice, traders and townspeople boycotted foreign goods, and ordinary people joined demonstrations and constructive work. Different communities and social groups adapted the programme to their own concerns. Thus option A is correct; the other choices wrongly exclude the public or describe the movement as British-controlled or military.