Final answer:
Karl Marx is best known for writing 'The Communist Manifesto', a pivotal work that established the ideology of Marxism and critiqued the capitalist system. Co-authored with Friedrich Engels in 1848, it significantly influenced political thought and the structure of many states in the 20th century.
Step-by-step explanation:
Karl Marx, a renowned German philosopher and economist, is best known for writing c) The Communist Manifesto. In collaboration with Friedrich Engels, Marx published this groundbreaking piece in 1848. The Communist Manifesto is considered one of the most influential political writings in history, presenting Marx's revolutionary theory of society and his critique of capitalism which laid the groundwork for the ideology of Marxism.
Despite other notable works such as 'Das Kapital', The Communist Manifesto remains a definitive text in examining class struggles and the prediction of a society transitioning from capitalism through socialism to communism. This manifesto has significantly shaped political thought and has had wide-reaching impacts on global political landscapes, particularly influencing states that adopted Marxist principles in the 20th century.
Marx's critical analysis of the capitalist system and his vision for a communist society continue to be topics of academic and ideological discussion, underlining the enduring relevance of his work.