The correct answer is option 1: Communism. Communism is an ideology that advocates for the abolition of private property and the establishment of a classless society. It believes that society is divided into two main classes: the bourgeoisie (the owners of the means of production) and the proletariat (the working class).

According to communist doctrine, the class struggle between the bourgeoisie and the proletariat is a central aspect of society. The proletariat is believed to be exploited by the bourgeoisie, with the surplus value created by the working class being appropriated by the capitalist class. Communism aims to overthrow the bourgeoisie and establish a society in which the means of production are collectively owned and controlled.

Options 2, 3, and 4 do not have class struggle as a central part of their doctrines. Capitalism, in contrast to communism, supports private ownership and a market-based economy. Fascism, on the other hand, emphasizes authoritarianism, nationalism, and the supremacy of the state. Socialism advocates for a more equitable distribution of wealth and resources, but its approach to achieving this goal may vary and may not necessarily center around class struggle.

Therefore, the correct answer is option 1: Communism.