Two masthead lights are prescribed for a power-driven vessel of 30 meters in length. What is the minimum required horizontal distance between those two masthead lights?

Why B is correct

33 CFR §84.03(a) requires the horizontal distance between two masthead lights to be not less than one quarter of the vessel's length. One quarter of 30 meters is 7.5 meters. The 50-meter figure is the maximum, not the minimum, and the 10-meter figure applies only to vessels 50 to 60 meters on the Western Rivers under §84.03(e).