BOTH INTERNATIONAL & INLAND While underway in fog, you hear the fog signal of another vessel ahead. If a risk of collision exists, you must __________.

Under Inland Navigation Rules, for the condition where 'While underway in fog, you hear the fog signal of another vessel ahead. If a risk of collision exists, you must', the correct requirement is: 'slow to bare steerageway and navigate with caution'. This standard ensures clear navigational intent and collision avoidance.