The tingey company has 500 obsolete microcomputers that are carried in inventory at a total cost of $720,000. If these microcomputers are upgraded at a total cost of $100,000, they can be sold for a total selling price of $160,000. As an alternative the microcomputers can be sold in their present condition for $50,000. The sunk cost in the situation is

A. $720,000

B. $160,000

C. $50,000

D. $100,000