If \(y = tan^{-1}(\frac{3x-x^3}{1-3x^2}), \frac{-1}{\sqrt{3}} < x < \frac{-1}{\sqrt{3}}\)

• A. 3
• B. \(\frac{3}{1+x}\)
• C. –\(\frac{3}{1+x^2}\)
• D. \(\frac{3}{1+x^2}\)