What Does a Statement of Work Document Do

What does a statement of work document do?

A) It documents in detail the work that must be completed for a particular object, and includes specifics such as tasks, deliverables, standards, payment schedule, and work timeline.
B) It documents the intentions of two or more parties to enter into a binding agreement, or contract, and is sometimes used between an informal handshake and the legally binding signatures on contracts.
C) It is a legally binding contract or part of a contract that defines, in plain language and in measurable terms, the aspects of a service provided to a customer, such as the service provided by an ISP.
D) It is a contract that defines the terms of future contracts between parties, such as payment terms or arbitration arrangements.