If ${\mu _0}$ and ${\varepsilon _0}$ denote the permeability and permittivity of free space,the dimensions of ${\mu _0}{\varepsilon _0}$ are:

• A
  $L{T^{ - 1}}$
• B
  ${L^{ - 2}}{T^2}$
• C
  ${M^{ - 1}}{L^{ - 3}}{Q^2}{T^2}$
• D
  ${M^{ - 1}}{L^{ - 3}}{I^2}{T^2}$