Final answer:
The arm switch must be in the arm position to use the selective jettison system.
Step-by-step explanation:
The arm switch must be in the arm position to use the selective jettison system. This switch is a safety mechanism that ensures the system is armed before activating it, preventing unintentional jettisoning of objects.
Once the switch is in the arm position, the selective jettison system can be used to selectively jettison specific objects or payloads.