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