Final answer:
Carts and trucks should not be obstructing or left unattended in any corridor, exit, or means of egress to ensure that these areas remain clear for safe and efficient evacuations in emergencies.
Step-by-step explanation:
In regards to safety protocols for material transportation in a building, the correct answer is: No, they should not obstruct or be left unattended. Carts and trucks used to move materials should always be parked or stored in a manner that does not block or obstruct any corridor, exit enclosure, or other means of egress. These areas need to be kept clear to ensure a safe and efficient evacuation in case of an emergency. Obstructions can slow down the evacuation process and even lead to accidents or injuries. Therefore, it's important to follow proper safety guidelines to maintain clear exit routes at all times.