Concept:Energy stored in a capacitor combination is given by U=21CeqV2.Explanation:Let C1=C and C2=2C.For the series combination, the equivalent capacitance is Cs=C1+C2C1C2=C+2CC(2C)=32C.For the parallel combination, the equivalent capacitance is Cp=C1+C2=3C.The energy stored in the series combination is Us=21CsVs2.The energy stored in the parallel combination is Up=21CpVp2.Since the energies are equal, Us=Up.This gives 21⋅32CVs2=21⋅3CVp2.Cancelling common factors, we get 32Vs2=3Vp2.So Vp2Vs2=29.Taking the square root, VpVs=23.Thus, Vs:Vp=3:2.Answer:The correct ratio is 3:2, which is Option B.