To Calculate the Opportunity Cost Per Unit,you Divide the Decrease

To calculate the opportunity cost per unit,you divide the decrease in the quantity of the forgone item by the

A) decrease in the quantity of the other item.
B) price of the item forgone.
C) price of the item obtained and then multiply by the price of the item forgone.
D) price of the item obtained.
E) increase in the quantity of the other item obtained.