The correct option is A 13(i0)2Tt0
From t=0→t0
From the graph
i=3i0i0t (from straight line equation)
We know that, H=i2Rt2
Total heat produced
=∫t00(3i0t0)2 R dt+(3i0)2R(2t0−t0)+(i0)2R(3t0−2t0)
=3(i0)2Rt0+9(i0)2Rt0+(i0)2Rt0=13(i0)2Rt0
Hence, option (b) is correct.