#### Answer

H; $15$

#### Work Step by Step

Since triangles $ABC$ and $DEF$ are similar, the lengths of their sides are proportional.
We can find the proportion by dividing two similar side lengths:
$24\div32=0.75$
Since the proportion of one side length is $0.75$, and the triangles are similar, the proportion of the other side lengths will also be $0.75$. We can find the side length of side $DF$ by multiplying the known side length, $AC$, by $0.75$
$20\times0.75=15$
The side length of $DF$ is $15$.