Classify each statement as a definition, postulate, or theorem. Select the correct answer from each drop-down menu.

Through any two points, there is exactly one line. (Theorem, Postulate, Definition)
A line segment is part of a line and is bounded by two endpoints. (Theorem, Postulate, Definition)
If two lines intersect, then each pair of opposite angles are congruent. (Theorem, Postulate, Definition)