$\int \frac{\mathrm{dx}}{(\mathrm{x}+1) \sqrt{\mathrm{x}^2+1}}=$

• A

  $\frac{1}{\sqrt{2}} \operatorname{Sinh}^{-1}\left(\frac{1+x}{1-x}\right)+c$
• B

  $\frac{1}{\sqrt{2}} \operatorname{Sinh}^{-1}\left(\frac{1-x}{1+x}\right)+c$
• Correct answer
  C

  $-\frac{1}{\sqrt{2}} \operatorname{Sinh}^{-1}\left(\frac{1-x}{1+x}\right)+c$
• D

  $-\frac{1}{\sqrt{2}} \operatorname{Sinh}^{-1}\left(\frac{1+x}{1-x}\right)+c$

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