Mark against the correct answer in each of the following:

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

$\int \sqrt{a x+b} d x=?$

A. $\frac{2(a x+b)^{3 / 2}}{3 a}+C$

B. $\frac{3(a x+b)^{3 / 2}}{2 a}+C$

C. $\frac{1}{2 \sqrt{a x+b}}+C$

D. none of these