1. The problem asks to write a true biconditional statement about angle bisectors. 2. A biconditional statement uses "if and only if" to show equivalence between two conditions. 3. The definition of an angle bisector is: a ray that divides an angle into two congruent angles. 4. Using the diagram, the red ray labeled "bisector" is the bisector of angle $\angle CBA$ formed by rays $\overrightarrow{BC}$ and $\overrightarrow{BA}$. 5. The true biconditional statement is: "A ray is the bisector of an angle if and only if it divides the angle into two congruent angles." 6. This means the ray is the bisector of the angle exactly when it creates two equal angles. 7. Therefore, the correct choices to form the biconditional are: "is the bisector of" and "if and only if". Final biconditional: **A ray is the bisector of an angle if and only if it divides the angle into two congruent angles.**