To determine which choice indicates that line segment \( AB \) is the perpendicular bisector of line segment \( CD \) when they intersect at point \( P \), we look for two conditions:
- \( AB \) must be perpendicular to \( CD \).
- \( P \) must be the midpoint of \( CD \), which means \( CP \cong DP \).
The correct choice that indicates \( AB \) is the perpendicular bisector of \( CD \) is:
Choice 3: \( AB \perp CD \) and \( CP \cong DP \)
This states that \( AB \) is perpendicular to \( CD \) and that segments \( CP \) and \( DP \) are congruent, meaning \( P \) is the midpoint of \( CD \).