I chose 50,000 but it was said that the answer choice was incorrect can you help me?

Question 10 X Your answer is incorrect. Try again. Swifty Corporation uses 10000 units of Part A in producing its products. A supplier offers to make Part A for $5. Swifty Corporation has relevant costs of $7 a unit to manufacture Part A. If there is excess capacity, the opportunity cost of not buying Part A from the supplier is O $20000. O $70000. O $0. O $50000