Explanation: Compulsory radiotelegraph installations on passenger vessels, critical for safety and communication, must undergo regular inspections to ensure operational readiness and compliance with international and domestic regulations. These vital systems are required to be inspected at least once every 12 months. This annual inspection ensures that all equipment is functioning correctly, meets technical standards, and can perform its intended safety functions. Option A is incorrect because while an initial inspection is required when the vessel is placed in service, the subsequent periodic inspections are annual, not every two years. Option B is incorrect as a three-year interval is too infrequent for compulsory safety equipment, and proximity to an FCC field office does not determine the inspection frequency. Option C describes a reporting requirement, the Annual Equipment Verification Report, which is distinct from the physical inspection frequency itself, though often related.