Why should you copy the NIS source files to an alternate directory prior to building the NIS maps?

A.
It is required that all NIS source files exist within the /var/yp directory type.

B.
It prevents overwriting the original source files during the build of the NIS maps.

C.
NIS is restricted from accessing source files that are located in the /etc directory.

D.
It provides a location to modify the passwd and shadow files to avoid propagating the root password throughout the NIS domain.