How would you avoid this scenario?

Anyone who knows just the host name and the listener name can have full control over the listener.
They can stop the listener and also obtain detailed information about the listener, database, and the
configuration of the application. How would you avoid this scenario?

A.
lock the listener

B.
hide the listener

C.
create multiple listeners

D.
run listener on a remote client

E.
set a password for the listener

F.
store listener.ora in a non-default location