Which of the following groupings of accounts includes only accounts that carry a normal debit balance?

a. Inventory, Cost of Goods Sold, Customer Refunds Payable, and Sales

b.Inventory, Delivery Expense, Cost of Goods Sold, and Estimated Returns Inventory

c.Sales Tax Payable, Inventory, Delivery Expense, and Customer Refunds Payable

d.Delivery Expense, Customer Refunds Payable, Estimated Return Inventory, and Sales