Two coils of self inductance $2 \mathrm{mH}$ and $8 \mathrm{mH}$ are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is

• A

  $16\mathrm{mH}$
• B

  $10\mathrm{mH}$
• C

  $6\mathrm{mH}$
• Correct answer
  D

  $4\mathrm{mH}$

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