A coil in the shape of square is placed in a variable magnetic field, which varies at the rate of dB /dt shown in figure. The magnitude of emf between points a and d along path abcd will be

Options

A. `[(L^2 /2) (dB /dt)]`
B. `[L^2(dB /dt)]`
C. `[-2L^2(dB /dt)]`
D. `[3(L^2 /2) (dB /dt)]`