Which two statements regarding fuel systems are true?

The assertion that tank airspaces must interconnect and that the jettison valve must be operable is true for aircraft fuel systems. Interconnecting tank airspaces allow for the equalization of pressure and fuel levels, which helps ensure that fuel can be drawn consistently across different tanks, especially during flight maneuvers. This is vital for maintaining balance and performance.

Additionally, having an operable jettison valve is essential for certain aircraft configurations. The jettison system allows for the release of fuel in an emergency situation or during specific flight phases, such as landing, enabling the aircraft to reduce weight quickly. This capability is crucial for safety and operational efficiency.

The other options, while related to fuel systems, do not accurately reflect the operational standards required for fuel management in aviation and thus do not contribute to a comprehensive understanding of the function and regulation of aircraft fuel systems.