You are proceeding against the current on a river in the Great Lakes System. You are meeting a downbound vessel. Both vessels are power-driven. The other vessel sounds one short blast. You must __________.

Correct Answer: Option D — sound one short blast

Under Inland Great Lakes rules, a downbound vessel with a following current has the right-of-way. When the downbound vessel initiates one short blast indicating a port-to-port passage, the upbound vessel must answer with one short blast and comply.