Which of the following is a primary source of entry into the debtors ledger?

The primary source of entry into the debtors ledger is sales invoices. Sales invoices are the documents used to record the sale of goods or services to customers on credit. They provide a detailed breakdown of the items sold, the quantity, the price, and any applicable taxes or discounts. When a sale is made on credit, a sales invoice is created and serves as the primary source of entry into the debtor's ledger. The debtor's ledger is a record of all amounts owed to the business by its customers. Each customer has their own account in the ledger, which shows the total amount owed, the payment history, and any outstanding balances. When a sales invoice is created, it is recorded in the debtor's ledger as an increase in the amount owed by the customer. Suppliers' invoices are used to record purchases made by the business from suppliers, and returns outwards notes are used to record returns of goods to the supplier. Payment vouchers are used to record payments made by the business to its suppliers or other creditors. None of these documents serve as a primary source of entry into the debtor's ledger. Therefore, the correct option is sales invoices.