Final answer:
If two line segments are congruent, they are perpendicular and form a 90° angle between each other.
Step-by-step explanation:
If two line segments are congruent, it means that they have the same length. Therefore, the correct answer is They are perpendicular, forming a 90° angle between each other. When two line segments are congruent, they can form a right angle with each other, but it is not necessary for them to be parallel or along the x-axis. In fact, congruent line segments can be at any angle to each other as long as they have the same length.