A rectangular coil PQ has 2n turns, an area 2a and carries a current 2I, (refer figure). The plane of the coil is at 60º to a horizontal uniform magnetic field of flux density B. The torque on the coil due to magnetic force is
(A) BnaI sin 60º
(B) 8 BnaI cos 60º
(C) 4 BnaI sin 60º
(D) none
