What action would you take to overcome this error without disrupting any existing database communications?

You manually create an additional listener process, L1, for databases PROD, PAYDB and FINDB. While
starting up the listener process, you get the following error message:
LSNRCTL> start l1
Starting /u01/app/oracle/product/10.1.0/db_1/bin/tnslsnr: please wait…
TNSLSNR for Linux: Version 10.1.0.2.0 – Production
System parameter file is /u01/app/oracle/product/10.1.0/db_1/network/admin/listener.ora
Log messages written to /u01/app/oracle/product/10.1.0/db_1/network/log/l1.log
Error listening on: (ADDRESS=(PROTOCOL=TCP)(HOST=144.23.230.185)(port=8899))
TNS-12542: TNS:address already in use
TNS-12560: TNS:protocol adapter error
TNS-00512: Address already in use
Linux Error: 98: Address already in use
Listener failed to start. See the error message(s) above…
What action would you take to overcome this error without disrupting any existing database
communications?

A.
stop and restart the listener process

B.
set the TNS_ADMIN environmental variable

C.
stop all running listener processes and restart the listener process

D.
change the port number to an unused port number and restart the listener process

E.
change the IP address to host machine name in the LISTENER.ORA file and restart the listener
process