What is a customer unit$-$level cost?

Option A

resources consumed for each unit sold to a customer.

Option B

resources consumed for each sales transaction.

Option C

resources consumed to service a customer regardless of the number of units or batches sold.

Option D

resources consumed in each distribution channel the firm uses to service customers.

Option E

resources consumed to sustain sales and service activities that cannot be traced to an individual unit, batch, customer, or distribution channel.