What involves walking or riding a given route to observe the condition of the facility?

Patrol duty involves moving through assigned routes or areas to monitor activity, detect irregularities, and observe the general condition of the facility. Patrolling can be conducted on foot or by vehicle and is a fundamental component of proactive security operations.

Posts (B) are stationary assignments.

Reserves (C) are backup personnel.

"None of the above" (D) is incorrect because patrol duty is the accurate answer.