Which of the following definitions of financial statement elements relating to income is correct?

A$.$Losses are decreases in equity from transactions affecting an entity except those that result from expenses or distributions to owners.

B$.$Revenues are inflows or other enhancements of assets of an entity from delivering or producing goods, rendering services, or carrying out other activities.

C$.$Expenses are outflows or other using up of assets of an entity from delivering or producing goods, rendering services, or carrying out other activities.

D$.$Gains are increases in equity from transactions affecting an entity except those that result from revenues or investments by owners.