Binding energy per nucleon vs mass number curve for nuclei is shown in the Figure. W, X, F and Z are four nuclei indicated on the curve. The process that would release energy is  

[c] Energy is released when stability increases. This will happen when binding energy per nucleon increases.$Reac\tan tProduct$Reaction [a] 60×8.5MeV =510MeV 2×30×5 =300MeV$Reaction\left[b\right]120\times 7.5=900MeV\left(90\times 8+30\times 5\right)=870MeV$Reaction [c] 120×7.5 =900MeV 2×60×8.5 =1020MeV$Reaction\left[d\right]90\times 8=720MeV\left(60\times 8.5+30\times 5\right)=600MeV$