Answer
Neither
Work Step by Step
Check the differences between consecutive terms:
$$1-1=0$$
$$2-1=1$$
$$3-2=1$$
$$5-3=2$$
Since differences are not common, it is not arithmetic.
Check the ratios between consecutive terms:
$$1:1=1$$
$$2:1=2$$
$$3:2=1.5$$
$$5:3=1.666...$$
Since ratios are not common, it is not geometric.