Which of the following is equivalent to the joule?

A.     ${\text{N}}\,{{\text{m}}^{\text{2}}}$

B.     ${\text{N}}\,{{\text{m}}^{ - 2}}$

C.     ${\text{kg}}\,{\text{m}}\,{{\text{s}}^{ - 2}}$

D.     ${\text{kg}}\,{{\text{m}}^{\text{2}}}{{\text{s}}^{ - 2}}$

D