Question

The best option for reason 9 of the proof is

Theorem 3.1 Two lines intersected by a transversal are parallel if and only if alternate interior angles are congruent.

Theorem 3.2 Two lines intersected by a transversal are parallel if and only if corresponding angles are congruent.

Theorem 3.3 Two lines intersected by a transversal are parallel if and only if alternate exterior angles are congruent.

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