🔍 Key Concepts
• Simplex vs. duplex operation in marine VHF communications
• Role of the International Telecommunication Union (ITU) in standardizing frequencies
• Meaning of frequency pairs in radio communication
💭 Think About
• Ask yourself: does a duplex channel usually use one frequency or two for communication between ship and shore?
• Think about what the ITU does: does it focus on one country (like the U.S.) or international standards?
• Which choice best reflects a formal, global system for organizing how VHF channels are used?
✅ Before You Answer
• Verify whether duplex means using separate transmit and receive frequencies.
• Confirm that ITU work products are typically international, not U.S.-only.
• Check which option clearly mentions a pair of frequencies and common (shared) use.