Let $$f(x) = \begin{cases} \frac{1}{3}, & x \le \frac{\pi}{2} \\ \frac{b(1 - \sin x)}{(\pi - 2x)^2}, & x > \frac{\pi}{2} \end{cases}$$. If $$f$$ is continuous at $$x = \pi/2$$, then the value of $$\int_0^{3b-6} |x^2 + 2x - 3| \, dx$$ is :

A

5

B

2

C

3

D

4