Final answer:
The correct answer is c, which states that marketers must make sure all firms in the distribution chain can earn an adequate profit to maintain customer access. In competitive markets, prices usually equate to the marginal costs, accounting for both private and social costs.
Step-by-step explanation:
The most accurate statement is c. Marketers must ensure that firms in their channels of distribution must make an adequate profit or they will be cut off from their customers. This is because businesses must cover not only the private costs of production but also consider the social and environmental costs, which affects the pricing of their products. In a perfectly competitive market, the price of goods tends to equal the marginal cost of production, reflecting both firm's costs and broader social costs.
Companies in a competitive market do not have the power to set prices above the equilibrium determined by market supply and demand. Consequently, these firms must be efficient to survive, which includes having a supply chain capable of generating profit for all parties involved. Price elasticity of demand can indeed affect the ability to cover costs but does not make it 'virtually impossible' as suggested by option d; rather, it shapes the strategy a business might use to set prices.