Explanation: NAVTEX stations transmit on medium frequencies (MF), primarily 518 kHz, which utilize *ground wave* propagation. Ground waves travel along the surface of the Earth and follow its curvature, especially effectively over seawater. This allows NAVTEX signals to be reliably received well beyond the visual horizon. A typical ground wave range for these frequencies and power levels is 200 to 400 nautical miles, providing essential maritime safety information to vessels in coastal and offshore waters. Options A and D describe ranges far too short or modes of propagation (line-of-sight) that are characteristic of higher frequencies (VHF/UHF), not MF. Option C's upwards of 1000 nautical miles during the daytime is generally too extensive for consistent and reliable ground wave coverage.