How Is Socialism Defined

How is socialism defined?

A) An economic system under which all property is communally owned and no social distinctions are made on the basis of people's ability to produce.
B) An economic system in which the means of production are largely in private hands and the main incentive for economic activity is the accumulation of profits.
C) A means of production in which property is collectively owned, but the means of production and distribution remain in private hands.
D) An economic system under which the means of production and distribution are collectively owned.