Correct Option: D. Pay-in-slip Explanation of the Correct Answer: A pay-in-slip is a document used to deposit cash or cheques into a bank account. It serves as a formal record of the transaction and is typically filled out by the person making the deposit. The pay-in-slip includes important details such as:

• The date of the deposit
• The amount of cash or cheques being deposited
• The account number into which the funds are being deposited
• The name of the depositor

When you go to the bank to deposit cash, you fill out a pay-in-slip, which the bank uses to record the transaction in their system. This document is crucial because it provides a clear and official record of the cash being deposited, ensuring that both the bank and the depositor have a reference for the transaction. Why the Other Options Are Incorrect: A. Invoice - An invoice is a document issued by a seller to a buyer, detailing the products or services provided and the amount owed. It is primarily used for sales transactions and accounts receivable, not for recording cash deposits. Therefore, it does not serve as a source document for cash paid into a bank. B. Cheque Book - A cheque book contains cheques that can be used to make payments from a bank account. While cheques can be deposited into a bank, the cheque book itself does not record cash being paid into the bank. Instead, it is a tool for making payments, not for documenting deposits. C. Credit Note - A credit note is issued by a seller to a buyer, indicating a reduction in the amount owed, often due to returns or allowances. Like invoices, credit notes are related to sales transactions and do not pertain to cash deposits into a bank account. Summary of Key Points:

• The pay-in-slip is the main source document for recording cash deposits into a bank.
• It includes essential details such as the date, amount, account number, and depositor's name.
• Other options like invoices, cheque books, and credit notes are not relevant for documenting cash deposits.

Revision Summary:

• Pay-in-slip is the correct document for cash deposits.
• It provides a formal record of the transaction.
• Other options (invoice, cheque book, credit note) do not serve this purpose.
• Understanding source documents is crucial for accurate financial record-keeping.