A square wire loop with 2 m sides in perpendicular to a uniform magnetic field, with half the area of the loop in the field. The loop contains a 20 V battery with negligible internal resistance. If the magnitude of the field varies with time according to `B = 0.042 – 0.87` t, with B in tesla & t in sec.
What is the total emf in the circuit ?

Options

A. 20.0V
B. 18.26V
C. 21.74V
D. None of these