If two parallel lines are intersected by a transversal, then which of the options below is necessarily true?

Correct option is D

Concept Used

When two parallel lines are intersected by a transversal, specific angle relationships are formed, such as corresponding angles, alternate interior angles, and interior angles on the same side of the transversal.

Solution

Option A: Incorrect. Corresponding angles are equal, not supplementary.

Option B: Incorrect. Alternate interior angles are equal, not supplementary.

Option C: Incorrect. Vertically opposite angles are equal, not supplementary.

Option D: Correct. Interior angles on the same side of the transversal are supplementary (sum = $$180^\circ$$​).