Explanation: INMARSAT-C SES antennas are designed to be omnidirectional, meaning they can transmit and receive signals from all horizontal directions (or a very wide cone). This characteristic is crucial for maritime applications where the ship is constantly moving, pitching, and rolling. An omnidirectional antenna ensures reliable communication with the geostationary INMARSAT satellites without requiring complex, active stabilization systems to track the satellite's position. Highly directional antennas (A, B, C) would necessitate continuous, precise pointing to maintain a satellite link, which is impractical and expensive for the low-cost, robust INMARSAT-C system. The system's design prioritizes reliability and simplicity over high data rates, making an omnidirectional antenna the ideal choice.