The Average Kinetic Energy of a Nitrogen Molecule at Room $\degree$

The average kinetic energy of a nitrogen molecule at room temperature (20 $\degree$ C) is

A) 2 *10 ^{- 21} J.
B) 4 *10 ^{- 21} J.
C) 6 * 10 ^{- 21} J.
D) 8 *10 ^{- 21} J.
E) 1 *10 ^{- 20} J.