The area of the region bounded by the curve $y=f(x)$, the $X$ -axis and the lines $x=a$ and $x=b$, where $-\infty<a<b<-2$ is
(a) $\int_{a}^{b} \frac{x}{3\left[\{f(x)\}^{2}-1\right]} d x+b f(b)-a f(a)$
(b) $-\int_{a}^{b} \frac{x}{3\left[\{f(x)\}^{2}-1\right]} d x+b f(b)-a f(a)$
(c) $\int_{a}^{b} \frac{x}{3\left[\{f(x)\}^{2}-1\right]} d x-b f(b)+a f(a)$
(d) $-\int_{a}^{b} \frac{x}{3\left[\{f(x)\}^{2}-1\right]} d x-b f(b)+a f(a)$