Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then in parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be:

The correct option is D 1:4

Since the two wires have the same material, length and diameter, they have the same resistance. Let the resistance of each wire be R.
Let applied potential difference be V.
Rseries = R1 + R2 = R + R = 2R
Pseries = V²/Rseries = V²/(2R). (i)
1/Rparallel = 1/R1 + 1/R2
Rparallel = R/2
Pparallel = V²/Rparallel = 2V²/R (ii)
Dividing (ii) from (i),
Pseries/Pparallel = 1/4