If g is the inverse of the function $\mathrm{f}(\mathrm{x})$ and $\mathrm{g}(\mathrm{x})=\mathrm{x}+\tan \mathrm{x}$ then, $\mathrm{f}^{\prime}(\mathrm{x})=$

• A

  $1+\sec ^2 x$
• Correct answer
  B

  $\frac{1}{1+\sec ^2 f(x)}$
• C

  $\frac{1}{1+\sec ^2 g(x)}$
• D

  $1+\sec ^2 f(x)$

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