Detailed Answer
Answer (A) is correct.
A continuous (rolling) budget is one that is revised on a regular (continuous) basis. Typically, a company continuously extends such a budget for an additional month or quarter in accordance with new data as the current month or quarter ends. For example, if the budget cycle is 1 year, a budget for the next 12 months will be available continuously as each month ends. The principal advantage of a rolling budget is that it requires managers always to be thinking ahead.