What light configuration should a power-driven vessel exhibit when anchored?

A power-driven vessel that is anchored is required to exhibit an all-round white light. This specific light configuration serves a crucial purpose in ensuring the vessel's visibility to other mariners, particularly during nighttime or in conditions of reduced visibility. The all-round white light must be shown from where it can be seen all around, helping other vessels to determine the position and status of the anchored vessel.

The other options provided do not align with the requirements set forth in the COLREGs. For example, two red lights vertically indicate a vessel that is constrained by its draft, not one that is simply anchored. Similarly, a combination of a green and a white light would be inappropriate, as the green light signifies a sailing vessel’s starboard side while under way, not a vessel at anchor. Finally, having a white light at the bow and a red light at the stern does not fulfill the standard for an anchored vessel, as it does not provide the all-round visibility needed for safety. Thus, the all-round white light configuration is essential for alerting nearby vessels to the stationary status of the power-driven vessel.