Answer:
Pentagon 2
Explanation:
~A "Line of Symmetry" is the imaginary line where you can fold an image and have both halves match exactly.
The reason that this line is not a line of symmetry is simple, look at where it crosses. For the first pentagon, it is really easy to see that it has a line symmetry marked. For the third pentagon, you can either look at it slanted, or rotate it in your mind until the symmetry line is facing straight up and down. You can also see that it crosses through a point and a straight line, just like the first line of symmetry did. The fourth pentagon is the same way. Just rotate it and it can look like 1 and 3. The second pentagon's line goes through 2 corners, which immediately means that it is different from the others. If you rotate it, it can not get to a point where it looks like 1, 3, or 4, meaning 2 is the answer.