I really need help completing and understanding this problem. Very much appreciated.

A company purchased $1,800 of merchandise on July 5 with terms 2/10, n/30. On July 7, it returned $200 worth of merchandise. On July 28, it paid the full amount due. Assuming the company uses a perpetual inventory system, and records purchases using the gross method, the correct journal entry to record the payment on July 28 is: Multiple Choice Debit Merchandise Inventory $1,600; credit Cash $1,600. Debit Cash $1,600; credit Accounts Payable $1,600. Debit Accounts Payable $1,600; credit Merchandise Inventory $32; credit Cash $1,568. Debit Accounts Payable $1,800; credit Cash $1,800. Debit Accounts Payable $1,600; credit Cash $1,600