The correct answer is C.
In a market economy, the main economic decisions are reached in the markets, where producers and consumers interact freely and, as a result, prices and amounts produced and supplied are determined. Hence, there is no interventionism performed by the goverment or any economic authorities.
Considering the case of the producer who wants to ensure sales in a market economy, he will not have to take care of whether it will be legally required to buy his products or not. This system simply does not exist in a market economy, as there is no economic authority governing the markets, hence a legal requirement cannot be established over certain goods. On the contrary, the producer will have to care about the preferences of consumers (option A), the performance of the competition (option B) and the affordability and the budget constraints of the potential customers (option C).
