A conducting ring of mass 2kg and radius 0.5 m is placed ring on a smooth horizonatal plane. The ring carries a current of i\[i=4A\]. A horizontal magnetic field B = 10 T is switched on at time t = 0 as shown in fig. The initial angular acceleration of the ring will be

• A. \[40\,\pi \,rad\,{{s}^{-2}}\]
• B. \[20\,\pi \,rad\,{{s}^{-2}}\]
• C. \[5\,\pi \,rad\,{{s}^{-2}}\]
• D. \[15\,\pi \,rad\,{{s}^{-2}}\]