In the formula, $a=3b{c}^2$, $a$ and $c$ have dimensions of electric capacitance and magnetic field intensity respectively. The dimensions of $b$ in $\mathrm{S}.\mathrm{I}.$ system are

• Correct answer
  A

  $\left[{\mathrm{M}}^{-3}{\mathrm{L}}^{-2}{\mathrm{T}}^4{\mathrm{Q}}^4\right]$
• B

  $\left[{\mathrm{M}}^{-3}{\mathrm{T}}^4{\mathrm{Q}}^4\right]$
• C

  $\left[{\mathrm{M}}^{-3}{\mathrm{T}}^3\mathrm{Q}\right]$
• D

  $\left[{\mathrm{M}}^{-3}{\mathrm{L}}^2{\mathrm{T}}^4{\mathrm{Q}}^{-4}\right]$

Hence, the correct answer is option: 'A'.