The correct answer is A. Petty cash system.
A petty cash system is a small amount of cash that is kept on hand to pay for minor expenses. It is often used in businesses to pay for items such as office supplies, postage, and travel expenses. The petty cash system is based on the imprest system, which means that a fixed amount of cash is set aside for the petty cash fund. When money is spent from the petty cash fund, a receipt is obtained and the amount is recorded in a petty cash journal. At the end of each month, the petty cash fund is replenished to the original amount.
The petty cash system is a convenient way to handle small expenses. It is also a good way to control spending, as all expenses must be authorized and recorded. However, the petty cash system can be time-consuming to manage, and it is important to keep track of the petty cash fund to ensure that it does not run out of money.
The other options are not correct because they are not systems for handling small expenses. A cash book is a book that is used to record all cash transactions. A cash receipts journal is a book that is used to record all cash receipts. A discount is a reduction in the price of an item.