The integral $\; \int x cos^{-1}(\large\frac{1-x^{2}}{1+x^{2}}) dx\;(x > 0)\;$ is equal to :

Question

$(a)\;-x+(1+x^{2}) tan^{-1}x +c \qquad(b)\;x-(1+x^{2}) cot^{-1}x +c \qquad(c)\;-x+(1+x^{2}) cot^{-1}x +c \qquad(d)\;x-(1+x^{2}) tan^{-1}x +c$