Office Supplies Bought on Account Were Returned for Credit and Recorded

Office Supplies bought on account were returned for credit and recorded with a debit to Accounts Payable and a credit to Merchandise Inventory.This error would cause:

A) the period end Cost of Goods Sold to be understated.
B) the period end Cost of Goods Sold to be overstated.
C) the period's net income to be overstated.
D) None of these is correct.