Read this quote by karl marx from the communist manifesto.

“the history of all hitherto existing society is the history of class struggles.”

what is a marxist principle that the above quote to explain?
a)the means of production should be in the hands of the upper class.
b)socialism would never uphold the rights of the working class.
c)society should remain a competition between the classes.
d)the best society is one without socioeconomic classes.