For one mole of a monoatomic gas with molar mass $M$,the root mean square velocity is $u_{rms}$. What is the relationship between $u_{rms}$ and the average kinetic energy $E$?

• A
  $u_{rms} = \sqrt{\frac{3E}{2M}}$
• B
  $u_{rms} = \sqrt{\frac{2E}{3M}}$
• C
  $u_{rms} = \sqrt{\frac{2E}{M}}$
• D
  $u_{rms} = \sqrt{\frac{E}{3M}}$