A) positive is the correct answer. When the height of the metacenter (the point at which the buoyant force acts) is greater than the height of the center of gravity, the upright equilibrium position is stable. This is because the metacenter is above the center of gravity, creating a righting moment that will return the vessel to the upright position if disturbed. This positive stability ensures the vessel will resist capsizing and remain upright. The other options are incorrect because: B) unstable - The upright equilibrium is actually stable in this case. C) neutral - Neutral stability would occur if the metacenter and center of gravity were at the same height. D) negative - Negative stability would occur if the center of gravity was above the metacenter, leading to a capsizing moment.