Describing VHF transmissions as "line of sight" means:

Correct Answer: Option D — Both b) and c) are true

VHF propagation is limited by the curvature of the earth, necessitating line-of-sight paths. The effective range is directly proportional to the height of the antennas involved. Under normal conditions, ship-to-shore VHF communication is typically limited to approximately 25 nautical miles, depending on the height of the respective antennas.