ABC decides to switch to Step$-$down method and cost allocation sequence is based on a ranking of percentage of services provided to other support departments, which of the following best describes this procedure?

A$.$ Maintenance department$$s costs are allocated to Power, Assembly and Finishing, then Power$$s costs are allocated to Assembly and Finishing.

B$.$ Power department$$s costs are allocated to Assembly and Finishing, then Maintenance$$s costs are allocated to Assembly and Finishing.

C$.$ Power department$$s costs are allocated first to Maintenance, Assembly and Finishing, then Maintenance$$s costs are allocated to Assembly and Finishing.

D$.$ Maintenance department$$s costs are allocated to Assembly and Finishing, then Power$$s costs are allocated to Assembly and Finishing.