Why does the process continue to run?

User1 is attempting to assist user2 with terminating user2’s process 1234. User1 entered
the following: kill -9 1234 Why does the process continue to run?

A.
You can kill a process only if you are root.

B.
You need to kill the process with a stronger kill signal.

C.
You can kill the process only with the pkill command.

D.
You can kill only a process that you own.