Recall the Application About the Demand and Price for Margarine

Recall the Application about the demand and price for margarine to answer the following question(s) .
-Recall the Application.The margarine industry is an example of a constant-cost industry because as the total output of the industry changes,the price of the key inputs to the production of margarine don't change.As a result,

A) the demand decreases by the same amount.
B) the supply increases by the same amount.
C) the unit of cost is unaffected by changes in total output.
D) the unit of cost is affected by changes in total output.