Which of the following is the correct order for applying activity$-$based costing steps in a service business?

a$.$ Allocate overhead costs to customers based upon activity$-$base usage, determine activity rates for each activity, and identify activities

b$.$ Identify activities, determine activity rates for each activity, allocate overhead costs to customers based upon activity$-$base usage, and invoice the customer

c$.$ Identify activities, determine activity rates for each activity, and allocate overhead costs to customers based upon activity$-$base usage

d$.$ Determine activity rates for each activity, identify activities, and allocate overhead costs to customers based upon activity$-$base usage