Final answer:
Anarchism and Marxism were historically linked with Socialism, with anarchists and Marxists supporting socialist revolutions aimed at overhauling society and government, especially noted in the early to mid-20th century.
Step-by-step explanation:
Anarchism and Marxism were once associated with Socialism because many anarchists and nihilists supported the socialists' call for revolution and the complete overhaul of government and society in the early to mid-20th century. The correct answer to fill in the blank is c) Marxism.
Anarchism is an ideology that advocates for the absence of government, urging for a society organized on the principles of voluntary cooperation and mutual aid, contrasting with the hierarchical structures and governance of states. Mikhail Bakunin, a well-known anarchist, clashed with Karl Marx on the role of the government in achieving a socialist society but shared the Marxist critique of capitalism and its intrinsic class struggles.
The economic expansion of Russia with the help of western investments, an increase in factories and rail networks, failed to match political and social reforms leading to revolutionary sentiment among reformers. These reformers, including both anarchists and Marxists, aimed for a revolutionary transformation of society to attain social equality - an objective deeply intertwined with the ideological backbone of socialism at that time.