When an operator is trying to log off the system displays this message: you have running jobs?? What does this mean?（）

A. One or more processes are running in the background, preventing log off.
B. One or more processes are paused, requiring operator input prior to logging off.
C. At least one process is running in the background and it will keep running after the operator logs off
D. At least one process is running in the background using nohup and it will terminate when the operator logs off