In the diagram, which must be true for point D to be an orthocenter? BE, CF, and AG are angle bisectors. BE ⊥ AC, AG ⊥ BC, and CF ⊥ AB. BE bisects AC, CF bisects AB, and AG bisects BC. BE is a perpendicular bisector of AC, CF is a perpendicular bisector of AB, and AG is a perpendicular bisector of BC.