Technician a Says That When a CNG Commercial Vehicle Is

Technician A says that when a CNG commercial vehicle is serviced in a facility not specifically designed for NG vehicles, 50% of the roll-up doors must be raised at least 12-inches (25cm) from the ground. Technician B says that when a CNG commercial vehicle is serviced in a facility not specifically designed for NG vehicles, the extraction and ventilation system must be turned on a be capable of exchanging 5 times the total shop volume of air per hour. Who is correct??

A) ?Technician A only
B) ?Technician B only
C) ?Both A and B
D) ?Neither A nor B