Answer:
D) Where price equals marginal cost.
Explanation:
Agricultural commodities are the closest thing to a perfectly competitive market since there are many buyers and many suppliers, they are all price takers since no supplier nor buyer has enough market power to fix or alter the equilibrium price.
The accounting profit maximizing quantity will always be where marginal revenue = marginal costs. In this case, marginal revenue = price.
This profit maximizing quantity is the same for all markets, but generally perfectly competitive firms are unable to make any economic profit, unlike other markets where economic profits are possible in the short run.