Answer:
C) midsegment
Explanation:
An angle bisector cuts an angle in half. LM does not do this.
An altitude extends from a vertex perpendicular to the opposite side. LM does not do this.
A midsegment goes from the midpoint of one side to the midpoint of another side. LM does this.
A perpendicular bisector splits a side in half, forming a right angle. LM does not do this.