Final answer:
The minimum clearance between a rooftop gas-fired appliance and the roof edge is typically 3 Feet (1 meter), adhering to general safety guidelines and local building codes.
Step-by-step explanation:
The minimum allowed clearance between a rooftop gas-fired appliance and the edge of the roof often depends on local building codes and the manufacturer's instructions. However, as per the general guidelines, the correct answer would be B) 3 Feet (1 meter). This clearance is essential not only for the optimal operation of the appliance but also for ensuring the safety of any personnel that needs to be on the roof for maintenance or repair reasons.