A.It helps when trying to find where a requirement came from.

B.It helps to produce unambiguous requirements.

C.It helps to analyze the impacts of change in requirements.

D.It helps to produce verifiable requirements.

A.To register the reason why a requirement exists.

B.To follow the evolving history of a requirement.

C.To provide unique identification to a requirement.

D.To make it possible to revert a requirement to a previous version.