Correct Answer - D
In case (i), R = `2Omega`
Case (ii), `R = 2 + 2 = 4 Omega`
Case (iii), `(1)/(R) = (1)/(2) + (1)/(2) = 1 rArr R = 1 Omega`
Since, `H = (V^(2))/(R)xxt`, As voltage in the three cases for equivalent resistance is same
so, `H prop (1)/(R)`. So heat produced is maximum in case (iii).