What must a 50-meter power-driven vessel display at night?

A power-driven vessel that is 50 meters in length must display specific lights at night to ensure that it is visible to other vessels and to adhere to the COLREGs (International Regulations for Preventing Collisions at Sea). According to these regulations, a power-driven vessel over 50 meters is required to show two masthead lights.

The two masthead lights should be placed one above the other with the upper light being at least one meter higher than the lower light and must be visible over a range of 225 degrees from the bow of the vessel. This arrangement helps to communicate the size and nature of the vessel to others on the water, providing a clear indication of its type and heading.

The other options do not fulfill the regulations for a vessel of this size. A single white light would not provide sufficient information for other vessels to identify the type of vessel, and displaying a masthead light only would not meet the requirements either, as vessels over 50 meters must show two. Choosing not to display any lights at all would violate safety regulations and increase the risk of collisions at night.