If \( \int \dfrac{(x^2+1)e^x}{(x+1)^2}\,dx = f(x)e^x + C \), where \( C \) is a constant, then \( \dfrac{d^3 f}{dx^3} \) at \( x=1 \) is equal to:
\( -\dfrac{3}{4} \)
\( \dfrac{3}{4} \)
\( -\dfrac{3}{2} \)
\( \dfrac{3}{2} \)