Answer
The graph labeled as (d) matches with $a_n=18(-\frac{3}{2})^{n-1}$
Work Step by Step
$a_n=a_1r^{n-1}$
$a_n=18(-\frac{3}{2})^{n-1}$
$a_1=18$
$r=-\frac{3}{2}$
Since $a_1\gt0$ and $r\lt-1$, the terms of the sequence are alternating between positive and negative with their absolute values increasing.
