Explanation: A main receiver on a United States ship must be capable of operating across a range of frequencies to ensure comprehensive maritime safety and communication. The 350 to 515 kHz band covers important Medium Frequency (MF) channels, including the international NAVTEX frequencies (e.g., 490 kHz, 518 kHz) and the traditional 500 kHz international distress frequency (primarily for radiotelegraphy, though now largely superseded by GMDSS for primary distress alerting). The 100 to 200 kHz band, which is in the Low Frequency (LF) range, is also crucial. This band contains frequencies allocated for maritime use, including certain long-range navigational warnings, meteorological information broadcasts, and general maritime communications, particularly from shore stations to ships. Regulations for shipboard radio equipment, under both international treaties (like SOLAS) and national rules (like FCC Part 80 for commercial maritime operations), often mandate the capability to receive in these LF bands to ensure a ship can gather all necessary maritime safety information (MSI). The other options are incorrect: * **A) 600 to 700 kHz:** While adjacent to the MF maritime band, it is not typically singled out as a mandatory *additional* distinct band for primary safety monitoring. * **B) 1000 to 1200 kHz:** This range falls within the AM broadcast band and is not relevant for mandatory maritime safety communication capabilities. * **D) 516 to 615 kHz:** This band is immediately adjacent to and significantly overlaps with the given 350 to 515 kHz band. It does not represent a distinctly separate frequency range requirement like the LF band (100-200 kHz).