Answer: D)Revolts by the Working Class.
Explanation:
Marx and Engels lived, wrote and created during the Industrial Revolution. They are the ideological creators of socialism and communism; they witnessed the difficult conditions in which the working class lived. Their views formed the first trade unions, and they are the initiators of the idea of protecting workers' rights. One of these elements of protecting workers' rights is certainly the strikes and revolts of the working class.
