Drone exam · Ground-risk mitigation Safety Which person is most clearly uninvolved? Select one answer A A trained observer briefed for the flight. B A worker who was never briefed and is walking normally through the site. C The remote pilot. D A designated site marshal following the briefing. Check answer Correct answer: B. A worker who was never briefed and is walking normally through the site. Employment at the site does not by itself make a person involved in the UAS operation.