A power-driven boat 50 meters or more in length must display red and _____________________ sidelights, a masthead light, a stern light, and a _____________________ light.

In maritime navigation, the proper display of lights on vessels is critical for safe operations, particularly in low visibility conditions. For power-driven boats that are 50 meters or more in length, the International Regulations for Preventing Collisions at Sea (COLREGs) mandate specific lighting requirements to ensure that these vessels are easily identifiable to other mariners.

The correct answer highlights that such vessels must display red and white sidelights. The red light is positioned on the port (left) side of the vessel, while the white light is placed on the starboard (right) side. This specific configuration allows other vessels to determine the direction the power-driven boat is heading, as well as its length and type, which is essential for collision avoidance.

Additionally, a masthead light and a stern light are also required for vessels of this size. The masthead light, situated at the front of the boat, is a white light that shines forward over a specific arc, contributing to the indicator of the boat's position and heading. The stern light, also a white light, illuminates the rear of the vessel.

The requirement for a white light, along with the red sidelights, aligns with the guidelines established to standardize navigation aids across different types of vessels,