Final answer:
All small unmanned aircrafts over .55 pounds must be registered with the FAA regardless of their intended use.
Step-by-step explanation:
According to 14 CFR part 48, a person must register a small unmanned aircraft (UA) with the Federal Aviation Administration (FAA) if it weighs more than 0.55 pounds (250 grams) and less than 55 pounds (25 kilograms) at takeoff, including everything that is on board or otherwise attached to the aircraft. This registration is required for both hobbyist (recreational) and commercial use. Therefore, option A is correct: All civilian small UAs weighing greater than .55 pounds must be registered regardless of its intended use.