What does an operation (op) script do?

What does an operation (op) script do?

A.
Instructs the Junos OS to perform a set of actions whenever the script is run manually or called
by another script

B.
Instructs the Junos OS to perform a set of actions based on its location in the configuration.

C.
Instructs the Junos OS to perform a set of actions during the process of activating configuration
changes.

D.
Instructs the Junos OS to perform a set of actions automatically based on operational status of
the device.