Johnston Controls began operation in $2021$ using FIFO inventory methods. In $2022,$ management decided they should have chosen LIFO to more accurately portray financial position and performance. The beginning $2022$ inventory using FIFO was $$120,000.$ Under the LIFO method the beginning inventory would have been $$160,000.$ The adjustment to inventory for the accounting principle change for $2021$ would be $q,$

A$.$ $$40,000$ credit

B$.$ $$40,000$ debit

C$.$ $$20,000$ debit

D$.$ $$0$