A $\rm ms^{-2} = m^2s^{-2} + m^2s^{-2}$

B $\rm m^2s = m^2s^{-2} + m^2s^{-2}$

C $\rm m^2s^{-2} = m^2s^{-2} + m^2s$

D $\rm m^2s^{-2} = m^2s^{-2} + m^2s^{-2}$