Answer
$D.$
Work Step by Step
Starting with the graph of figure 21, taking a=3, $f(x)=3^{x}$,
and then
transforming each point via symmetry relative to the origin,
we obtain this graph.
$y=-f(-x)$ is symmetric relative to the origin with $y=f(x).$
We look for $ y=-3^{-x}\qquad$... choice $D.$