You are correct, the answer is D) Ballasting the double bottom tanks. Ballasting the double bottom tanks increases the transverse stability of a merchant vessel by lowering the vessel's center of gravity. This increases the righting moment, which is the force that counteracts heeling and helps the vessel return to an upright position. Ballasting the double bottom tanks is an effective way to improve transverse stability and increase the vessel's resistance to capsizing. The other options would not have the same positive effect on transverse stability. Deballasting deep tanks (A) or positioning a heavy lift cargo on the main deck (B) would raise the center of gravity, decreasing stability. Raising the cargo booms (C) would have a negligible impact on stability.