$\int \frac{x^3}{x^4+3 x^2+2} d x=$

• Correct answer
  A

  $\log \left(\frac{x^2+2}{\sqrt{x^2+1}}\right)+\mathrm{c}$
• B

  $\log \left(x^2+2\right)-2 \log \left(x^2+1\right)+\mathrm{c}$
• C

  $\log \left(\frac{\left(x^2+2\right) x}{\sqrt{x^2+1}}\right)+\mathrm{c}$
• D

  $\log \left(\frac{x^2+1}{\sqrt{x^2+2}}\right)+\mathrm{c}$

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