How did the architects of Hagia Sophia accomplish their fusion of the central-plan form and the basilica?

A) By placing several domes on the nave
B) By subdividing the side aisles
C) By matching the height of intersecting basilicas
D) By placing a hemispherical dome on a square base

The architects of Hagia Sophia, Isidore of Miletus and Anthemius of Tralles, accomplished the fusion of the central-plan form and the basilica by placing a hemispherical dome on a square base, using pendentives to transition from the square base to the circular dome, thereby creating a revolutionary design that allowed for a vast and open interior space.