If $A_{1}, A_{2}$ be two arithmetic means and $G_{1}, G_{2}$ be two geometric means between two positive numbers a and $b$, then $\frac{A_{1}+A_{2}}{G_{1} G_{2}}$ is cqual to
(a) $\frac{a}{b}+\frac{b}{a}$
(b) $\frac{1}{a}+\frac{1}{b}$
(c) $\sqrt{\frac{a}{b}}+\sqrt{\frac{b}{a}}$
(d) $\frac{a b}{a+b}$