The correct answer is B) Sound only fog signals until the other vessel is sighted. This is the correct answer because under the International Regulations for Preventing Collisions at Sea (COLREGS), when vessels are in sight of one another in fog, they are required to indicate their relative position and movements by sounding the appropriate fog signals, but are not required to sound whistle signals to indicate course changes. Sounding two short blasts would indicate that the vessel is altering course to the right, which may not accurately reflect the situation. Instead, the proper action is to sound the appropriate fog signal (such as one prolonged blast) to indicate the vessel's presence and movements, without necessarily signaling a course change. The other options are incorrect because A) would be signaling a course change that may not be accurate, C) would mean not sounding any signals at all, and D) would only be appropriate if the vessel is actually changing course.