When approaching a lock entrance, the visual signal displayed when a single lock is ready for entrance is a flashing __________.
Official USCG Answer & Rule Citation
Correct Answer: Option D — green light
In accordance with USACE and USCG inland navigation regulations for lock operations, a flashing green light indicates that the lock is ready for immediate entrance. Conversely, a flashing red light indicates the lock is not ready, and a flashing amber light serves as a cautionary signal for approaching vessels.
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