The dimensional formula for the magnetic field is

• Correct answer
  A

  $\left[{\mathrm{M}\mathrm{T}}^{-2}{\mathrm{A}}^{-1}\right]$
• B

  $\left[{\mathrm{M}\mathrm{L}}^2{\mathrm{T}}^{-1}{\mathrm{A}}^{-2}\right]$
• C

  $\left[{\mathrm{M}\mathrm{T}}^{-2}{\mathrm{A}}^{-2}\right]$
• D

  $\left[{\mathrm{M}\mathrm{T}}^{-1}{\mathrm{A}}^{-2}\right]$

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