BOTH INTERNATIONAL & INLAND Which requirement must be met in order for a stand-on vessel to take action to avoid collision?

Correct Answer: Option B — Risk of collision must exist.

Under Inland Navigation Rules, for the condition where 'Which requirement must be met in order for a stand-on vessel to take action to avoid collision', the correct requirement is: 'Risk of collision must exist.'. This standard ensures clear navigational intent and collision avoidance.