Explanation: VHF (Very High Frequency) transmissions primarily travel via line-of-sight propagation. Signals in this range (30-300 MHz) typically penetrate the Earth's ionosphere rather than being refracted (bounced back to Earth) by it. Therefore, ionospheric refraction does not normally extend the range of VHF transmissions. In contrast: A) Salt water ingress into coaxial cable introduces significant signal loss (attenuation) and impedance mismatches, severely reducing the power reaching the antenna and thus limiting range. B) The power level setting directly affects the strength of the transmitted signal. More power generally leads to a stronger received signal and greater range. C) Vessel antenna height is crucial for line-of-sight communications. Higher antennas overcome the Earth's curvature more effectively, extending the radio horizon and thus the transmission range.