The correct answer is A) she shall turn off her sidelights when not making way. According to the International Regulations for Preventing Collisions at Sea (COLREGS), a vessel restricted in her ability to maneuver is required to display all-round red and green sidelights when underway, but when not making way, she shall turn off her sidelights and display a stern light, a masthead light, and a red and white all-round flashing light or shape of two diamonds in a vertical line. This requirement helps other vessels identify the restricted vessel's status and maneuver accordingly. The other answer choices are incorrect because: B) vessels engaged in fishing have the right-of-way over vessels restricted in their ability to maneuver, C) the whistle signal for a vessel restricted in her ability to maneuver is one prolonged blast followed by two short blasts, and D) the shape of two diamonds in a vertical line is used to indicate a vessel restricted in her ability to maneuver when not making way, not while underway.