Answer
Arithmetic sequence.
Work Step by Step
In order for a sequence to be arithmetic, the difference of all consecutive terms must be constant.
Here: $a_2-a_1=-5-2=-7$
$a_3-a_2=-12-(-5)=-7$
$a_4-a_3=-19-(-12)=-7$
Thus we can see that the difference is constant, thus it is an arithmetic sequence.