The correct answers are:
Definition of midpoint; Given; and Transitive Property.
Step-by-step explanation:
One of our givens is that B is the midpoint of AC. The definition of a midpoint is a point that is an equal distance from each midpoint of a segment; this means that AB would equal BC by definition of midpoint.
We are given that BC is congruent to DE.
Algebraically, the transitive property states that if a = b and b = c, then a = c. For this problem, we have AB = BC, and BC = DE, so AB = DE.