Mark against the correct answer in each of the following:

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

$\int \sqrt{e^{x}-1} d x=?$

A. $\frac{2}{3}\left(e^{x}-1\right)^{3 / 2}+C$

B. $\frac{1}{2} \cdot \frac{\mathrm{e}^{\mathrm{x}}}{\sqrt{\mathrm{e}^{\mathrm{x}}-1}}+\mathrm{C}$ e

C. $2 \sqrt{e^{x}-1}-2 \tan ^{-1} \sqrt{e^{x}-1}+C$

D. none of these