Which FAR lists the requirements for general operating and flight rules?

The choice identifying Part 91 as the correct answer is accurate because Part 91 of the Federal Aviation Regulations (FAR) establishes the general operating and flight rules for aircraft in the United States. This section provides comprehensive guidelines covering aspects such as the operation of aircraft, the responsibilities of pilots, and the adherence to safety procedures while conducting flight operations. These regulations apply to a wide range of aircraft, including those not operated under commercial regulations, thereby setting the foundational rules that all pilots must follow to ensure safe flight operations.

Part 71 relates primarily to the designations of controlled airspace and does not govern flight operations directly. Part 121 addresses operating requirements for scheduled air carriers and commercial operations, while Part 135 deals with on-demand operations and commuter services. Both of these parts have more specific guidelines tailored to commercial aviation rather than general operating rules, which is why Part 91 stands out as the comprehensive source for general operating and flight regulations.