The statement that best supports Karl Marx's argument that "The history of all hitherto existing society is the history of class struggles" is:
Women led a march on the Palace of Versailles to demand cheaper bread prices.
This event exemplifies class struggle, as it demonstrates the laboring class (in this case, the women and working populace) rising against the economic difficulties imposed by those in power and seeking to address their immediate needs. It illustrates the conflict between different social classes and their struggles for better living conditions, which is a key theme in Marxist theory.