A solid cast iron disk, 1 m in diameter and 0.2 m thick, is used as a flywheel. It is rotating at 350 rpm. It is brought to rest in 1.5 s by means of a brake. If the mass density of cast iron is 7200 kg/m3, the torque exerted by the brake will be nearly

• A. 3.5 kNm
• B. 4.5 kNm
• C. 5.3 kNm
• D. 6.3 kNm