The correct answer is A) If making way, she would show masthead lights at night. This is correct because a vessel carrying three vertical lights (with the highest and lowest being red and the middle being white) is displaying the navigation lights required for a power-driven vessel underway at night. According to the International and Inland Navigation Rules, a power-driven vessel underway must display masthead lights, sidelights, and a stern light when operating at night. The other answer choices are incorrect because: B) Vessels do not display three balls during the day to indicate the same lighting arrangement, C) Vessels displaying these navigation lights must still show anchor lights if at anchor, and D) The fog signal for this vessel would be a prolonged blast, not a rapid ringing of a bell.