The correct answer is C. Conflict
Step-by-step explanation:
Karl Marx was an important sociologist, economist, and philosopher known for his multiple publications that dealt with society, economy, and politics. In terms of society, Karl Marx proposed societies are organized in different classes each with different levels of power which leads to conflict or class struggle commonly between the ruling classes and those that are dominated. Additionally, for Marx this conflict or class struggle was the base for the evolution and development of societies and the structures in them, considering dominating classes in history have changed leading to different economic and social systems as in the case of Capitalism that was the result of the bourgeoisie dominating the proletariat. Therefore the element Karl Marx believed social structure evolve through is conflict and especially the conflict in term of class struggle.