[tex]\sqrt[n]{a}=a^{\frac{1}{n}}\\\\\text{Therefore}\\\\\sqrt3=3^\frac{1}{2}\\\\\sqrt[5]{3}=3^\frac{1}{5}\\\\\text{We have}\\\\(\sqrt3)(\sqrt[5]3)=3^\frac{1}{2}\cdot3^\frac{1}{5}\qquad\text{use}\ a^n\cdot a^m=a^{n+m}\\\\=3^{\frac{1}{2}+\frac{1}{5}}=3^{\frac{5}{10}+\frac{2}{10}}=3^{\frac{7}{10}}\\\\Answer:\ \boxed{D.\ 3^{\frac{7}{10}}}[/tex]
