The correct answer is B) lying to the south of a northern quadrant buoy. In the cardinal system of navigation, the color and shape of the buoy indicate the direction of the danger. A northern quadrant buoy (colored black and white vertically) marks an area of danger to the south of the buoy. This means that if a northern quadrant buoy is present, you would expect any hazards or obstructions to be located to the south of the buoy. The other answer choices are incorrect because they do not align with the cardinal system principles. Dangers would not be directly under the buoy (A), to the east of an eastern quadrant buoy (C), or to the south of an eastern quadrant buoy (D), as these positions are not indicated by the cardinal buoy system.