The correct answers are A) the Communist Manifesto and C) Das Kapital.
The two works written by Karl Marx are the Communist Manifesto and Das Kapital.
The "Communist Manifesto" was written by Karl Marx and Friederich Engels in 1848. The purpose of the Manifesto was serving as the foundation of Communist League. Later, it also served as the base of Communist and socialist parties in Europe. The other Marx's publication was "Das Capital," in 1868, in which Marx explains his point of view about capitalism and elaborate critics and projects its self-destruction. Both works are considered the pillars of Communism and represented a major influence in countries such as the Soviet Union and China.