What Is the Definition of Expenses

What is the definition of expenses?

A) Increases in stockholders' equity that a firm earns by providing goods or services for its customers
B) The obligations that an entity must pay at some time in the future because of past transactions or events
C) Decreases in a company's resources that a firm incurs in the process of earning revenues
D) The economic resources of an entity that can be usefully expressed in money terms
E) None of the above