The correct answer is (b) -s
The best explanation: Sometimes it may happen that some programs ignore the SIGTERM signal (15) and continue their execution normally. In such a case, the process can be killed by using SIGKILL signal (9). This signal can’t be generated at the press of a key, so we have to use KILL with the signal name preceded with -s option. For example, to kill a job with PID 184 use the following command: