Final answer:
A polygon has a line of symmetry if it can be folded along a line so that the two halves match exactly.
Step-by-step explanation:
The polygon has a line of symmetry if it can be folded along a line so that the two halves match exactly. To determine the number of lines of symmetry, we need to analyze the shape of the polygon. If the polygon has rotational symmetry, then it will have infinite lines of symmetry. If the polygon has reflection symmetry, then it will have 1 line of symmetry. If the polygon does not have any of these symmetries, then it will have 0 lines of symmetry.