The correct answer is D.
Pure market economies do not exist because when markets are allowed to freely function, and economic decisions are reached by the interaction of individuals, firms and goverment in the markets, these lead to sharply unequal outcomes and social welfare is threatened. On the other hand, command economies where goverments make all economic decisions are extremely inefficient.
In turn, mixed market economies are established, where economic authorities implement income redistribution systems that reduce income inequalities and generate fairer market outcomes for all the individuals that conform the society. Therefore, the redistribution systems and the intervention of the goverment in the markets, are part of the regular functioning of this type of economies.