One of the two identical capacitors having the same capacitance C, is charged to a potential $\mathrm{V}_1$ and the other is charged to a potential $\mathrm{V}_2$. If they are connected with their like plates together, then the decrease in the electrostatic potential energy of the combined system is

• A

  $\frac{\mathrm{C}}{4}\left(\mathrm{~V}_1^2-\mathrm{V}_2^2\right)$
• B

  $\frac{C}{4}\left(V_1^2+V_2^2\right)$
• Correct answer
  C

  $\frac{C}{4}\left(V_1-V_2\right)^2$
• D

  $\frac{\mathrm{C}}{4}\left(\mathrm{~V}_1+\mathrm{V}_2\right)^2$

Hence, the correct answer is option: 'C'.