Look at the Graphic Representation of Sociology's Family Tree

Look at the graphic representation of sociology's family tree. Given that they're both very influential in the classical stage of sociological theory, why are Karl Marx and Emile Durkheim depicted so far apart?

A) Marx's work is no longer considered very important.
B) Durkheim was greatly influenced by Marx, but not vice versa.
C) Emile Durkheim wasn't really a sociologist; he thought of himself more as a psychologist.
D) The theoretical schools they founded are very different.
E) Durkheim was French, while Marx was born in Germany.