Assertion (A) Increase in the number of wage-earners led to emergence of two sets of people in the society, the wage-earners and wage providers. Karl Marx termed these two classes, opposed to each other, as proletariat and bourgeoisie and causative factor for the emergence of trade unions.
Reason (R) After the industrial revolution, concentration of free labourers under one roof took place on a large scale. In order to resist the exploitation of employers, the labourers had no other alternative but to make a common stand.