Step 1: Understanding Parallel Lines.
Parallel lines are two straight lines that are always equidistant from each other and never meet, no matter how far they are extended. This is because they have the same slope.
Step 2: Verifying the Options.
- Option (1): Two straight lines that cannot intersect each other, meaning they are parallel, is the correct definition.
- Option (2): Lines that can intersect are not parallel lines.
- Option (3): A zig-zag line is not parallel, as it changes direction.
- Option (4): A straight line does not specifically describe a parallel line.
Conclusion:
Therefore, the correct answer is (1) Two straight lines which cannot intersect each other.