Which geometric principle is used to justify the construction below?

• A. A line perpendicular to one of two parallel lines is perpendicular to the other
• B. Two lines are perpendicular if they intersect to form congruent adjacent angles
• C. When two lines are intersected by a transversal and alternate interior angles are congruent, the lines are parallel
• D. When two lines are intersected by a transversal and the corresponding angles are congruent, the lines are parallel