What is the requirement for speed at KGTR until on base?

The correct requirement for speed at KGTR (which refers to a specific airport or region) until on base is 200 KIAS. This is typically dictated by standard operating procedures for aircraft in terms of maintaining an appropriate approach speed while adhering to air traffic control regulations.

At or below 10,000 feet, the Federal Aviation Administration (FAA) and other regulatory bodies require aircraft to maintain a speed of 250 knots indicated airspeed (KIAS) when flying within controlled airspace. However, as aircraft approach their landing configuration, speed reductions are necessary for safe maneuvering, especially during the base leg of an approach. Maintaining a speed of 200 KIAS allows pilots to have enough control over the aircraft while preparing for descent and final approach.

The other speeds mentioned, such as 150 KIAS, 250 KIAS, and 300 KIAS, do not align with the necessary balance of speed for approach and safety measures in the context of most standard operating procedures. Option B reflects a widely accepted practice aimed at minimizing risk during the critical phase of flight when turning onto the base leg before landing.