Under Certain Conditions, the Slope of the Marginal Revenue Product

Under certain conditions, the slope of the marginal revenue product curve reflects the combined effects of diminishing marginal returns and a declining price of the product the firm sells.What are these conditions?

A) The firm must be a price searcher in both the product market and the resource market.
B) The firm must be a price searcher in the product market, regardless of whether it is a resource price searcher.
C) The firm must be a price searcher in the product market but not necessarily in a perfectly competitive resource market.
D) The firm must be a price searcher in a perfectly competitive product market.
E) The firm must operate in a decreasing-cost industry.