For point D to be the orthocenter of triangle ABC, it is necessary that the lines drawn from each vertex (A, B, and C) to the opposite side are altitudes. This means that each of these lines is perpendicular to the side it intersects.
Therefore, for D to be the orthocenter, the correct statement is:
BE ⊥ AC, AG ⊥ BC, and CF ⊥ AB.
This indicates that line BE is perpendicular to side AC, line AG is perpendicular to side BC, and line CF is perpendicular to side AB. In this configuration, point D would indeed be the orthocenter of triangle ABC.