Answer
Geometric with a common ratio of $-\frac{1}{3}$.
Work Step by Step
Check if there is a common ratio by diving two consecutive terms:
$\dfrac{-6}{18}$ $=-\dfrac{1}{3}$;
$\dfrac{2}{-6}$ $=-\dfrac{1}{3}$ ;
$\dfrac{-{\dfrac{2}{3}}}{2}$ $=-\dfrac{1}{3}$.
The ratio is constant so this is geometric.The common ratio is $-\dfrac{1}{3}$
