Answer:
The journal entry should be:
Dr Merchandise Inventory account 50,000
Cr Retained Earnings account 50,000
Step-by-step explanation:
Since Oscar's merchandise inventory was understated by $50,000 because of the previous inventory method (LIFO), when the new method, FIFO, starts to be used then the merchandise inventory must increase by $50,000 as well as retained earnings.
Merchandise inventory is an asset account and it increases, therefore it should be debited.
Retained earnings is an equity account and it increases, therefore it should be credited.