B. All persons must register their small UA.
31 According to 14 CFR part 48, when would a small UA owner not be permitted to register it?
This is not the correct answer.
But tricky. All Small UAS must be registered, but not all persons are eligible to register a UAS.
Aha!, you say - UAS under 0.55 pounds are exempt from registration. But tricky, still as the FAA defines Small UAS as an unmanned aircraft between 0.55 pounds and 55 pounds.