Explanation: For radiotelephone installations aboard passenger vessels, especially those operating in the marine VHF band, the antenna design is critical for reliable communication over water. **Option B is correct** because marine VHF communication (typically 156-162 MHz) primarily uses ground waves (or surface waves) that propagate efficiently over seawater when the signal is **vertically polarized**. A **non-directional** (omnidirectional) antenna is essential because contact needs to be made with stations in any direction relative to the vessel. The antenna must also be **efficient** to maximize radiated power and received signal strength for safety and operational communications. **Option A is incorrect** as a specific 15-meter separation from a radiotelegraph antenna (which is less common now) is not a universal antenna requirement but rather an installation guideline if applicable. **Option C is incorrect** because while an emergency reserve antenna system for VHF Channel 16 (156.800 MHz) is a crucial safety requirement for passenger vessels, it describes a system redundancy rather than the inherent characteristics of the primary antenna itself. **Option D is incorrect** because testing and logging are operational and maintenance procedures, not fundamental requirements defining the antenna's physical or electrical characteristics.