Rank the Following Substances in Order of Increasing Average Velocity

Rank the following substances in order of increasing average velocity, assuming they are all at the same temperature: O₂, CO₂, Ar, He

A) O₂ < CO₂ < Ar < He
B) CO₂ < Ar < O₂ < He
C) Ar < O₂ < CO₂ < He
D) CO₂ < O₂ < Ar < He
E) He < O₂ < Ar < CO₂