Diagram B is a proper demonstration of an angle bisector.
Letter A is wrong because they are a set of intersecting ines.
Letter C is wrong because they are a set of parallel lines.
Letter D is wrong because they are also a set of perpendicular lines.
So, now, we know that Letter B is the correct answer. The reason for this is also because ∠ACD is bisected by line B.
I hope that this helped answer your question. Have a good day!
