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I think it is:

Pattern 3

Because:

In each row, the line style (plain, dotted, arrows) is consistent. That means the last item in the third row has to have "arrow" style. This eliminates patterns 8, 4, and if you look closely, 6 and 7 (there is one plain line in each of patterns 6 and 7).

And:

As you work left to right on any given row, the number of line intersections increases. Row one goes 1,2,3 ; Row two goes 1,5,9 ; row three goes 1,3,? . So the qualified pattern must have more than three line intersections. That gets rid of patterns 1, 2, and 5. Pattern 2 is an oddball which "suggests" intersections just outside the frame, but there's no precedent for that in the other patterns.

So: