Answer:
Both technicians are Right
Step-by-step explanation:
for technician A a vehicle may be considered Non-drivable in the case where the seat belt re-tractor is broken in a collision because the collision must be a very severe collision before the the seat belt re-tractor would be damaged completely . and with this damage the safety device in the car which is the seat belt will no longer function and it is very dangerous to drive without your seat belt.
for technician B the car can still be drivable because the damage to the Bumper doesn't pose a serious hazard threat to the driver of the vehicle in question.