suppose that fertilizer is necessary to produce wheat. if the price of fertilizer falls, the supply curve…

Brief Explanations:

Fertilizer is an input for wheat production. When the price of an input (fertilizer) falls, the cost of producing wheat decreases. Producers are more willing and able to supply wheat at each price level, so the supply curve of wheat shifts to the right. The supply - curve of fertilizer is not directly affected by its own price change in terms of a shift (a change in price of fertilizer causes a movement along its own supply curve, not a shift).

Answer:

D. wheat shifts to the right