Two metallic charged spheres of radii $R_{1}$ and $R_{2}$ having charges $Q_{1}$ and $Q_{2}$, respectively, are connected to each other. There is.
a. no ch?nge in the energy of the system
b. an increase in the energy of the system
c. always a decrease in the energy of the system
d. a decrease in energy of the system unless $Q_{1} R_{2}=Q_{2} R_{1}$