Final answer:
The Corresponding Angles Postulate allows us to justify the statement 'If <3 ≅ <8, then p || q'.
Step-by-step explanation:
The theorem or postulate that allows us to justify the statement 'If <3 ≅ <8, then p || q' is the Corresponding Angles Postulate. According to this postulate, if two angles are congruent (≅), then their corresponding sides are parallel (||).
To justify this statement using the Corresponding Angles Postulate, we would need additional information about the angles and their corresponding sides.
For example, if we are given that <3 and <8 are corresponding angles in two parallel lines cut by a transversal, then we can conclude that the lines containing those angles are parallel (p || q).