If a perpetual inventory system is in use, which of the following statements about transactions with customers is correct?

a) When a customer pays within the discount period, Accounts Receivable is credited for the full amount.

b) If a customer pays within the discount period, Sales Discounts is credited.

c) A sales return is recorded with entries that include a credit to Sales Returns & Allowances.

d) Sales of inventory are recorded by entries that include a credit to Cost of Goods Sold.