A US Company Buys Inventory from a Supplier in Canada and and Pays

A U.S. company buys inventory from a supplier in Canada and pays for the inventory in Canadian dollars (C$) . The inventory is converted to U.S. dollars on the U.S. company's balance sheet using what $/C$ exchange rate?

A) The rate when the inventory was paid for
B) The rate at the balance sheet date
C) The rate when the inventory was delivered
D) The rate when the inventory is sold