The relationship among most probable velocity,average velocity,and root mean square velocity is respectively:

• A
  $ \sqrt{2} : \sqrt{8/\pi} : \sqrt{3} $
• B
  $ \sqrt{3} : \sqrt{8/\pi} : \sqrt{2} $
• C
  $ \sqrt{8/\pi} : \sqrt{3} : \sqrt{2} $
• D
  $ \sqrt{2} : \sqrt{3} : \sqrt{8/\pi} $