B is correct.
From the service consumer’s perspective, there are two types of cost involved in
service relationships:
costs removed from the consumer by the service (a part of the value
proposition). This may include costs of staff, technology, and other resources,
which the consumer does not need to provide
costs imposed on the consumer by the service (the costs of service
consumption). The total cost of consuming a service includes the price charged
by the service provider (if applicable), plus other costs such as staff training,
costs of network utilization, procurement, etc. Some consumers describe this as
what they have to ‘invest’ to consume the service.