Which of the following is the MOST efficient mechanism to account for all staff during a speedy non-emergency evacuation from a large security facility?

A. Large mantrap where groups of individuals leaving are identified using facial recognition technology
B. Radio Frequency Identification (RFID) sensors worn by each employee scanned by sensors at each exit door
C. Emergency exits with push bars with coordinates at each exit checking off the individual against a predefined list
D. Card-activated turnstile where individuals are validated upon exit