Tìm nguyên hàm của hàm số f(x)

$A. \int f\left(x\right)dx=\frac{x^2}{2}-\frac{3}{2{\left(x+1\right)}^2}+C.$

$B. \int f\left(x\right)dx=\frac{x^2}{2}-\frac{3}{{\left(x+1\right)}^2}+C.$

$C. \int f\left(x\right)dx=\frac{x^2}{2}+\frac{3}{2{\left(x+1\right)}^2}+C.$

$D. \int f\left(x\right)dx=\frac{x^2}{2}+\frac{1}{{\left(x+1\right)}^2}+C.$