Which Estimating Technique Decomposes the Work into Lower,more Detailed Pieces,preferably

Multiple Choice

Which estimating technique decomposes the work into lower,more detailed pieces,preferably the lowest level of WBS work elements,for which estimates are prepared and then aggregates them into a total quantity for the project?​ 

A)  piece meal pricing 
B)  decomposition estimating 
C)  bottom-up estimating 
D)  grass roots estimating