The Most Original Contribution of Sinan to Ottoman Architecture Was

The most original contribution of Sinan to Ottoman architecture was:

A) To adapt the dome-over-a-square concept from Roman designs.
B) To use stained glass and flying buttresses to distribute weight.
C) To incorporate pre-Islamic pyramids, in defiance of the strictures of Islamic law.
D) To use up to eight slender pillars as hidden internal supports of the dome.