Sketch the region of integration for the following integral.
$\displaystyle \int_{0}^{\pi/4} \int_{0}^{3 / \cos(\theta)} f(r,\theta) \, r \, dr \, d\theta$
The region of integration is bounded by

A. $y = 0, y = x, \mbox{ and } x = 3$
B. $y = 0, x = \sqrt{9 - y^2}, \mbox{ and } y = 3$
C. $y = 0, y = x, \mbox{ and } y = 3$
D. $y = 0, y = \sqrt{9 - x^2}, \mbox{ and } x = 3$
E. None of the above