The atmosphere on a planet is possible only if [where $v_{rms}$ is the root mean square speed of gas molecules on the planet and $v_e$ is the escape speed on its surface]

• A
  $v_{rms} = v_e$
• B
  $v_{rms} > v_e$
• C
  $v_{rms} \leq v_e$
• D
  $v_{rms} < v_e$