In the scenario described, Lucy folds the paper so that point C lies directly on top of point D. When she unfolds the paper, point E is created as the intersection of the fold (the crease) and the line segment CD.
The crease formed by the fold would be the perpendicular bisector of line segment CD, meaning it intersects CD at its midpoint (point E) and forms right angles with the segment.
Thus, CE and DE are segments that share this midpoint E. Since E is the midpoint, the lengths of CE and DE are equal.
Based on this reasoning, the answer is: 3. The two segments are congruent.