A flat circular coil of n turns, area A and resistance R is placed in a uniform magnetic field B. The plane of coil is initially perpendicular to B. When the coil is rotated through an angle of 180∘ about one of its diameter, a charge Q1 flows through the coil. When the same coil after being brought to its initial position, is rotated through an angle of 360∘ about the same axis a charge Q2 flows through it. Then, Q2/Q1 is
(a) 1
(b) 2
(c) 1/2
(d) 0