The transformation of Non-Cooperation into a mass movement depended on what?

Correct answer: Participation of different groups and shared discontent

The governing concept is mass mobilisation: a national movement becomes broad only when different social groups connect their local grievances with a common political demand. Peasants, students, traders, workers and other participants gave Non-Cooperation a wider social base, while shared opposition to colonial rule linked their aims. Therefore option A is correct. The other choices are too narrow: British approval was not required, foreign trade was not the central cause, and soldier recruitment alone could not create a mass movement.