Which of the following best describes a cash-flow budget?

A cash-flow budget is primarily focused on tracking and estimating the income and expenditures over a specific period. This type of budget helps individuals or organizations manage their cash flow, ensuring that there is enough cash available to meet obligations as they arise. It provides insights into how much cash is expected to come in and how much is expected to go out, thereby allowing for effective planning and decision-making regarding spending and savings.

While the other options touch on aspects of financial management, they do not capture the essence of a cash-flow budget. For instance, outlining assets or comparing assets to liabilities focuses more on an organization's overall financial position rather than the timing of cash movements. Similarly, detailing expenditures and assets doesn't emphasize the cash flow aspect, which is critical for liquidity and operational efficiency. Hence, option C stands out as the most accurate depiction of what a cash-flow budget entails.