In a Rutherford scattering experiment when a projectile of charge $Z_1$ and mass $M_1$ approaches a target nucleus of charge $Z_2$ and mass $M_2$, the distance of closest approach is $r_0$. The energy of the projectile is :

• A

  Directly proportional to mass $M_1$
• B

  Directly proportional to $\mathrm{M}_1 \times \mathrm{M}_2$
• Correct answer
  C

  Directly proportional to $Z_1 Z_2$
• D

  Inversely proportional to $Z_1$

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