Which of the following is an example of retained earning?

Retained earnings refer to the portion of a company's net income that is retained in the business rather than being distributed to shareholders as dividends. This amount is accumulated over time and can be used for reinvestment in the business, debt repayment, or any other purpose that supports the company's growth and financial stability.

Profits that are not distributed to shareholders become part of retained earnings and are crucial for analyzing a company's financial health and its ability to reinvest in operations. This accumulation of profits contributes to the equity available to support business activities without requiring additional external financing.

In contrast, the other choices involve immediate cash flows or financing methods that do not relate to retained earnings. Monthly revenue pertains to the income generated over a specific period, equity financing refers to raising capital through the sale of shares, and bond financing involves borrowing through debt instruments. None of these options encapsulate the concept of retaining profits within the business, which is specifically represented by retained earnings.