Answer
From greatest to least:
Series, $R_{1}$, $R_{2}$, Parallel
Work Step by Step
Let $R_{1}$ = 2 ohm and $R_{2}$ = 1 ohms.
So in series, the equivalent Resistance is =$ R_{1} + R_{2}$ = 2 + 1 = 3 ohms
In parallel, the equivalent Resistance is = $\frac{R_{1} * R_{2}}{ R_{1} + R_{2}} = \frac{2 * 1}{ 2 + 1} = \frac{2}{3}$ ohms
From greatest to least: Series, $R_{1}$, $R_{2}$, Parallel
