Given: p: Angles XYZ and RST are vertical angles.
q: Angles XYZ and RST are congruent.

Which statement is logically equivalent to p → q?

If angles XYZ and RST are congruent, then they are vertical angles.
If angles XYZ and RST are not vertical angles, then they are not congruent.
If angles XYZ and RST are not congruent, then they are not vertical angles.
If angles XYZ and RST are vertical angles, then they are not congruent.