Explanation: 2182 kHz and Channel 16 (Ch-16) are international distress, urgency, safety, and calling frequencies. Their primary purpose is to establish initial contact between stations and to facilitate distress communications. To ensure these critical channels remain clear and available for emergencies and new calls, stations are required by regulation to change to an authorized working frequency as soon as initial contact is established and communication is confirmed. This keeps the calling channels free for others needing to make contact or declare distress. Options B, C, and D are incorrect. While stations must continuously monitor for distress calls (related to B) and good operating practice includes minimizing power (C), these are not the immediate regulatory requirement *after* establishing initial contact on these specific calling channels. Option D refers to specific listening silence periods on 2182 kHz for distress monitoring, not a general requirement for all communications after initial contact.