Total surface area of a cuboid = 2(lb + bh + lh). Here lb=340, bh=50, and lh=680. So TSA = 2 × (340 + 50 + 680) = 2140 square cm. 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 2140 cm².