Which of the following leaders was associated with the rise of Marxist theory in the context of revolution?

The rise of Marxist theory is primarily associated with Karl Marx himself, who co-authored "The Communist Manifesto" and wrote "Das Kapital," among other foundational texts. Marx's theories laid the groundwork for revolutionary thought by arguing that socioeconomic structures determine societal conditions and that class struggles drive historical change. His ideas advocate for the working class, or proletariat, to rise against the bourgeoisie or capitalist class to establish a classless society.

While other figures such as Lenin, Stalin, and Trotsky played significant roles in implementing Marxist principles and leading revolutions based on those principles—particularly the Bolshevik Revolution in Russia—the foundation of Marxism can be traced directly back to Marx. This makes him the pivotal figure in the emergence and development of Marxist theory, and therefore the correct choice in this context. Each of the other leaders interpreted, adapted, or expanded on Marx's ideas, but it was Marx who first articulated the theories that would inspire their actions and subsequent political agendas.