Which of the following is the best description of'top-down' budgeting?

a) Top management prepares a budget with little or no input from operating personnel

b) A series of budgets is prepared, from the most optimistic performance down to the most pessimistic

c) The process starts with sales, then progresses to production, materials usage and other functional budgets

d) The top level budget is non-financial, but more detailed budgets are progressively in more financial terms