2007-II-37

Ans: C
$\begin{array}{cl}
& \dfrac{3\sqrt{a}}{2} – \dfrac{a}{\sqrt{4a}} \\
= & \dfrac{3\sqrt{a}}{2} – \dfrac{a}{2\sqrt{a}} \\
= & \dfrac{3\sqrt{a} \times \sqrt{a}}{2\sqrt{a}} – \dfrac{a}{2\sqrt{a}} \\
= & \dfrac{3a}{2\sqrt{a}} – \dfrac{a}{2\sqrt{a}} \\
= & \dfrac{2a}{2\sqrt{a}} \\
= & \sqrt{a}
\end{array}$