The correct answer is B) The SART should be held as high as possible. The effective range of a SART (Search and Rescue Transponder) is maximized by placing it as high as possible above the water surface. This is because the radar signal emitted by the SART needs to be detected by the searching vessel's radar, and the higher the SART is positioned, the farther the signal can travel before being obstructed by the horizon or other obstacles. Holding the SART as high as possible, such as on an extended pole or line, allows the signal to reach the searching vessel's radar at a greater distance. The other options are incorrect because: A) Placing the SART in the water does not maximize its range, as the signal would be obstructed by the water surface. C) Switching to a "high" power position is not a feature of standard SART devices. D) Mounting the SART horizontally does not improve its performance, as the signal is designed to match the searching radar's sweep pattern.