Mark against the correct answer in each of the following:

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

$\int 3^{x} d x=?$

A. $3^{\mathrm{x}}(\log 3)+\mathrm{C}$

B. $3^{x}+C$

C. $\frac{3^{x}}{\log 3}+C$

D. $\frac{\log 3}{3^{x}}+C$