Answer
(c)
Work Step by Step
The graph of $3^{-x}$ is just the graph of $y=3^x$ reflected in the y-axis.
Also, $\lim\limits_{x \to -\infty}3^{-x} = \infty$
And, $\lim\limits_{x \to \infty}3^{-x}=0$
Thus, the answer is (c) which satisfies all the relations described above.
