The correct answer is D) All of the above. According to the US Coast Guard regulations, a lookout should report any relevant information to the person in charge of the vessel, including discolored water, floating objects, and shoals. These are all important factors that the captain or operator needs to be aware of to ensure the safe navigation of the vessel. Discolored water can indicate shallow or hazardous conditions, floating objects can pose a collision risk, and shoals or other underwater hazards must be identified to avoid grounding the vessel. Reporting all of these observations is crucial for the safe operation of the vessel and the protection of both the crew and the environment.