Since line segment AC is a perpendicular bisector of segment BD, we have the following key properties:
- It intersects segment BD at its midpoint, point E.
- It forms right angles with segment BD at point E.
Because E is the midpoint of BD, it follows that segments BE and DE are equal in length. Therefore, we can conclude that:
D. It must be the same length as segment DE.
So, the correct answer is D.