\( \frac{\text{d}}{\text{dx}} \left( \sin^{-1} \frac{2\text{x}}{1+\text{x}^2} \right) = \text{কত?} \)

A \( \frac{2}{1+\text{x}^2} \)

B \( \frac{2}{(1+\text{x}^2)^2} \)

C \( \frac{2\text{x}}{1+\text{x}^2} \)