Answer
$G.$
Work Step by Step
Starting with the graph of figure 21, taking a=3, $f(x)=3^{x}$,
and then
reflecting it across the y-axis $\qquad$... $y=f(-x)$
and then
shifting it to the right by 1 unit $\qquad$... $y=f(-x+1)$
... we obtain this graph.
We look for $ y=f(-x+1)=3^{-x+1}=3^{1-x}\qquad$... choice $G.$