What does Basic Empty Weight include?

Basic Empty Weight represents the total weight of the aircraft when it is not loaded with passengers, cargo, or usable fuel. It includes the weight of the airframe, the powerplant (engine), the complete operating equipment (instruments, systems, and avionics), and any optional equipment that has been installed. Additionally, it accounts for the oil in the engine at full capacity, which is crucial for the engine's operation, but it does exclude any fuel that is usable. Thus, choice C accurately reflects this definition by mentioning the standard airplane, optional equipment, and full oil, making it the correct answer.