What Differentiated Karl Marx's Views About the Possibilities for Social

What differentiated Karl Marx's views about the possibilities for social change from those of utopian socialists?

A) Unlike utopian socialists, who believed in cooperation, Marx was a realist whose views were based on scientific analysis and who saw class struggle as the basis for social change.
B) Marx believed that change could only occur through the destruction of all state power, while utopian socialists continued to encourage collaboration with government reformers.
C) Utopian socialists believed that social reform would come gradually but steadily, while Karl Marx argued that social change was not possible at all.
D) Marx believed that social reform would come through workers' cooperatives and government reform, while utopian socialists believed it could only come through class struggle.