Determine Whether the Sequence Is Geometric $- 1 , - 2 , - 4 , - 8 , \ldots$

Determine whether the sequence is geometric. If so, find the common ratio.
$- 1 , - 2 , - 4 , - 8 , \ldots$

A) 2
B) - 1
C) $\frac { 1 } { 2 }$
D) - 2
E) not geometric