Explanation: The range between markers is determined by the period of the oscillator and the speed of radio waves. 1. **Calculate the period (T) of the oscillator:** The frequency (f) is 27 kHz (27,000 Hz). The period T = 1/f = 1 / 27,000 Hz ≈ 0.000037037 seconds, or 37.037 microseconds (µs). This period represents the time difference between consecutive range markers. 2. **Convert time to range:** In radar and ranging applications, the signal travels out to a target and back. Therefore, the distance calculated from a time interval is a round-trip distance. A standard constant for range calculations is that a radio wave travels one nautical mile and returns in approximately 12.36 microseconds. 3. **Calculate the range between markers:** Range = (Period in µs) / (Time per nautical mile round trip) Range = 37.037 µs / 12.36 µs/NM ≈ 3.00 nautical miles. Therefore, the range between markers is 3 nautical miles. Options B, C, and D are incorrect as they do not result from this calculation.