Which of these is the main source document for recording cash paid into bank?

The main source document for recording cash paid into a bank is the pay-in-slip.
A pay-in-slip is a form provided by the bank that is filled out by the depositor when cash is deposited into their bank account. It includes important details such as the depositor's name, account number, and the amount of cash being deposited. The pay-in-slip also contains fields for the bank teller to acknowledge the deposit and stamp it.
When a person or business receives cash payments, they need to deposit that cash into their bank account. To do this, they would typically visit the bank and fill out a pay-in-slip with all the necessary information. The pay-in-slip serves as a record of the transaction and provides proof of the deposit made.
Unlike the other options mentioned, an invoice is a document that is issued by a seller to a buyer, indicating the products or services provided and outlining the amount due. A credit note is a document issued by a seller to a buyer to acknowledge a refund or credit towards a future purchase. A cheque book contains blank cheques that can be used to make payments from the account.
In summary, while invoices, credit notes, and cheque books have their own purposes, the pay-in-slip is the specific document designed for recording cash paid into a bank. It is important to use the correct source document to maintain accurate records of financial transactions.