Which Definition Best Describes the Process of Zero-Based Budgeting (ZBB)

Which definition best describes the process of zero-based budgeting (ZBB) ?

A) ZBB is an incremental budgeting process building on last year's shortfalls.
B) ZBB demands re-justification of the budget from ground zero each time a budget request was submitted.
C) ZBB is the best example of Lindblom's "muddling through."
D) None of the above.