In this scenario, Lexi folded her paper so that point C was on top of point D, which means that the line segment \( CD \) was bisected by the fold, with the fold creating equal segments on either side of point E where the fold intersects line segment \( CD \).
Given that the fold represents the segment bisector of \( CD \), the correct answer among the options is:
CD̅̅̅̅̅̅
This is because the fold bisected the segment \( CD \) and every point on the fold is equidistant from points C and D.