Line segment AB is drawn with midpoint M. A bisector is drawn through point M. Calley claims that any point on the bisector drawn through point M is equidistant from A and B. Which additional property must the bisector of overline AB have in order for Calley's claim to be true?
a. The bisector must be the same length as overline AB.
b. The bisector must be perpendicular to overline AB.
c. The bisector must intersect but not cross overline AB.
d. The bisector must contain a finite number of points.