The correct choice that indicates \( AB \perp CD \) is the perpendicular bisector of \( CD \) if they intersect at \( P \) is:
AB ⊥ CD and CP ≅ DP
This means that \( AB \) is perpendicular to \( CD \), and the segments \( CP \) and \( DP \) are congruent, which defines \( AB \) as the perpendicular bisector of \( CD \).