The correct answer is D) All of the above. Initial stability of a vessel can be improved by: A) Closing crossover valves between partly filled double bottom tanks, which helps prevent free surface effect and improves initial stability. B) Adding weight low in the vessel, which lowers the vessel's center of gravity and increases the righting moment, improving initial stability. C) Removing loose water, which prevents free surface effect and helps maintain a lower center of gravity, thus improving initial stability. All three of these measures help enhance the initial stability of a vessel by either reducing free surface effect or lowering the center of gravity, which are key factors in determining a vessel's initial stability.