The correct answer is A) LCG and LCB. The two points that act together to trim a ship are the Longitudinal Center of Gravity (LCG) and the Longitudinal Center of Buoyancy (LCB). The LCG represents the balance point of the ship's weight, while the LCB represents the balance point of the buoyant forces acting on the ship. The interaction between these two points determines the trim of the vessel, which is the difference in draft between the bow and stern. The other options are incorrect because they do not accurately represent the two points that act together to trim a ship. Option B refers to the Vertical Center of Gravity (VCG) and the LCG, which are involved in determining the ship's stability but not its trim. Option C refers to the Longitudinal Center of Flotation (LCF) and the LCB, which are related to the ship's motion but not its trim. Option D refers to the metacenter and the LCG, which are involved in determining the ship's stability but not its trim.