The Average Speed at Which a Methane Molecule Effuses at 28.5

The average speed at which a methane molecule effuses at 28.5 °C is 631 meters per second. The average speed at which an argon molecule effuses at this same temperature should therefore be

A) 253 m s^-1.
B) 315 m s^-1.
C) 400 m s^-1.
D) 502 m s^-1.
E) 631 m s^-1.