Final answer:
The correct answer is processing and recording credit memos, which is related to managing sales returns and allowances in a business setting.
Step-by-step explanation:
The business function related to sales returns and allowances is C) processing and recording credit memos. This involves issuing credit notes to customers when goods are returned or when there is a post-sale allowance granted. These credit memos reduce the amount owed by the customer, or refund part of the purchase price, and must be accurately recorded in the company's financial records.