Because of how it's worded the answer would most likely be number four
All the boats operating at night requires Navigation light.
Navigation light helps prevent collisions between boats and see if visibility is poor. The types of boat are : Rowboats, Tug boats, Vessels, Sailboat etc.
Various boats have different lightning color to show its use and side of the boat.
Since you didn't provide how tall the Monument was, I took the liberty to find it and it is 555 feet tall. So to convert to meters we must divide 555 by 3.28 or multiply it by 0.3048 (this is the method I used).
555 x 0.3048 = 169.164 meters
