Question

perpendicular lines form right angles
congruent supplements theorem
definition of angle bisector
definition of perpendicular
complement theorem

Explanation:

The statement "Perpendicular lines form right angles" is directly related to the geometric concept of perpendicularity. The "Definition of Perpendicular" precisely defines that when two lines are perpendicular, they intersect at a right angle (90 degrees). Other options like the Congruent Supplements Theorem deals with supplementary angles, the Definition of Angle Bisector is about splitting an angle into two equal parts, and the Complement Theorem is about angles that add up to 90 degrees (but not specifically about the relationship of perpendicular lines forming the right - angle).

Answer:

Definition of Perpendicular