Letter telling friend about an event attended

In the diagram, which must be true for point d to be anorthocenter? o be, cf, and ag are angle bisectors.be 1 ac, ag 1 bc, and cf 1 ab.be bisects ac, cf bisects ab, and ag bisects bc.be is a perpendicular bisector of ac, cf is aperpendicular bisector of ab, and ag is a perpendicularbisector of bc.