Which vessel is classified as "underway" according to maritime Rules?

Answer: C — purse seiner hauling her nets

A vessel is classified as "underway" when it is not at anchor, made fast to the shore, or aground, and it is capable of navigation. In this context, the purse seiner hauling her nets is actively engaged in fishing operations and is moving through the water, which qualifies it as underway. The cargo ship that is docked is tied to the pier and not moving. Similarly, the anchored sailing vessel is also stationary and therefore not classified as underway. The yacht on the hard refers to a boat that is on land or on a dry dock, which renders it immobile and not capable of navigating the waters. Thus, only the purse seiner, which is actively working and moving, fits the definition of being underway.