Historical Materialism is the fundamental tenet of Marxism in all its ‘classical’ varieties. History is the product not of conscious decisions and ideas, but of ‘material’ processes and conditions which can be identified and described without reference to the mental states of those who participate in them. It is the changes in these material conditions which make necessary and bring about those changes in social, political and institutional superstructures which in aggregate form the substance of history.

The correct answer is B.