The correct answer is C. revenue budget.
A revenue budget is a financial plan that projects how much revenue a company expects to generate in a given period of time. It is the starting point for an operating budget because it provides the foundation for all other budget categories, such as expenses, capital expenditures, and cash flow.
A cost budget is a financial plan that projects how much a company expects to spend in a given period of time. It is based on the revenue budget and takes into account the costs of goods sold, operating expenses, and other costs.
A material list is a list of the materials that a company needs to produce its products or services. It is used to calculate the cost of goods sold.
A list of investors is a list of people or organizations that have invested in a company. It is used to calculate the amount of capital that a company has available to spend.
In conclusion, the revenue budget is the starting point for an operating budget because it provides the foundation for all other budget categories.