A flat circular coil of `n` turns, area `A` and resitance `R` is placed in a uniform magnetic field `B`. The pane of coil is initially perpedicular of `B`. when the coil is rotated through an angle of `180^@` about one of its diameter, a charge `Q_1` flows through the coil When the same coil after charge `Q_2` flows through it. then `Q_2//Q_1` is
A. 1
B. 2
C. `1//2`
D. 0
