Mark against the correct answer in the following:

Mark $(\sqrt{)}$ against the correct answer in the following:

$\int_{1 / \pi}^{2 / \pi} \frac{\sin (1 / x)}{x^{2}} d x=?$

A. 1

B. $\frac{1}{2}$

C. $\frac{3}{2}$

D. none of these