Curved surface area of a cylinder = 2πrh. So CSA = 2 × 3.14 × 10 × 63 = 3956.4 square mm. This excludes the two circular ends. Think of a cylinder as many equal circular layers stacked up. So we find the circular base area πr² and multiply by the height. The answer is in cubic units, so the correct choice is 3956.4 mm².