Why You modified the *def file on your Security Gateway, but the changes were not applied?

You modified the *def file on your Security Gateway, but the changes were not applied. Why?

A.
There is more than one *.def file on the Gateway.

B.
You did not have the proper authority.

C.
*.def files must be modified on the SmartCenter Server.

D.
The *.def file on the Gateway is read-only.