During descent, what restriction is imposed on a jet aircraft?

The correct choice relates to the maximum speed restriction placed on a jet aircraft during descent. As aircraft descend, they must adhere to specific speed limits to ensure safe operation, known as maneuvering speeds, which can change based on altitude and configuration. This is especially crucial in the terminal phase of flight where the aircraft needs to maintain control and avoid exceeding structural limits, which could lead to greater resistance and potential instability.

In this phase, the aircraft may need to slow down to comply with air traffic control instructions, maintain safe separation from other aircraft, and ensure that they are within the safe operating parameters appropriate for the descent situation. Failure to observe maximum speed limitations can lead to unsafe flying conditions, including increased drag and the risk of stalling at lower altitudes.

Maximum altitude doesn't impose a restriction during descent as planes are generally reducing altitude, while maximum weight is typically more relevant during takeoff and landing phases rather than descent. Maximum distance is not a factor since descent does not inherently limit the distance traveled, but rather governs the descent profile and descent rate relative to time and altitude.