The $\_\_\_\_\_\_\_\_\_$ budgeting method consists of managers estimating overall project cost as well as the costs of the major subprojects that comprise it$.$ These cost estimates are then given to lower$-$level managers, who are expected to continue the breakdown into budget estimates for the specific tasks and work packages that comprise the subprojects. This process continues to the lowest level.

a$.$

bottom$-$up

b$.$

iterative$$

c$.$

top$-$down

d$.$

work element