Which type of vessel exhibits an all-round green light over an all-round white light?

The correct identification of a vessel exhibiting an all-round green light over an all-round white light corresponds to a specific type of fishing vessel: one that is engaged in trawling. Under the COLREGs, vessels engaged in trawling typically display this combination of lights to indicate their activity to other vessels. The all-round green light signifies that it is trawling, while the all-round white light is used as an additional indication of its status.

Other types of vessels display different lighting configurations according to their purposes and regulatory requirements. For example, a sailing vessel would typically show sidelights and a sternlight rather than the specific combination described in the question. Similarly, a vessel at anchor would display one all-round white light, while a power-driven vessel generally depicts a different set of lights that would not include the all-round lights mentioned.

Understanding the specific lighting configurations helps maintain safety and awareness on the water, enabling vessels to recognize and interpret the signals from others effectively based on their navigation and operational status.