Lines that intersect at 90 degrees

• A. Intersecting lines
• B. Parallel lines
• C. Skew lines
• D. Perpendicular lines

Answer: (D)

Perpendicular lines are two lines that meet and form a right angle. When the angle at their intersection is exactly 90 degrees, the lines are perpendicular, and four right angles appear around that point. This sets them apart from other cases: lines that cross without a right angle are simply intersecting lines; lines that never meet are parallel; lines that do not lie in the same plane and do not intersect are skew. So describing lines that intersect at 90 degrees directly matches the definition of perpendicular lines.