Total surface area of a cuboid = 2(lb + bh + lh). Here lb=378, bh=30, and lh=315. So TSA = 2 × (378 + 30 + 315) = 1446 square m. A cuboid has three pairs of equal rectangular faces: lb, bh, and lh. We add these three face areas and multiply by 2 to include the opposite faces. The answer is in square units, so the correct choice is 1446 m².