What is the approximate groundspeed in knots for an altitude range of 14,000 feet and above?

At an altitude of 14,000 feet and higher, the approximate groundspeed tends to be around 265 knots. This value accounts for the characteristics of aircraft performance at higher altitudes, where thinner air can affect both engine output and aerodynamic efficiency. The groundspeed at higher altitudes typically increases due to reduced drag and improved engine efficiency, allowing for higher speeds compared to lower altitudes where atmospheric conditions differ.

The other options do not adequately reflect the cruising speed norms for jet aircraft, which can reach much greater speeds at higher altitudes. Hence, the 265 knots figure represents a more accurate approximation of groundspeed for aircraft operating in that altitude range.