When a Firm Sells a Good or a Service,the Sale

When a firm sells a good or a service,the sale contributes to the nation's income

A) only if the buyer of the good or service is a household.
B) only if the buyer of the good or service is a household or another firm.
C) whether the buyer of the good or a service is a household, another firm, or the government.
D) We have to know whether the item being sold is a good or a service in order to answer the question.