Which distinctive feature of the Notre Dame Cathedral allowed it to accommodate its large stained glass windows?

A. its barrel vaults

B. its flying buttresses

C. its quadrant arches

D. its square bays

B. its flying buttresses. Builders employed the first true flying buttresses (during the 1180s) to increase the window size and secure the soaring 115-foot-high vault. The flying buttress, an arched, skeletal exterior support, counters the lateral thrust of the nave vault and transfers its weight outward, over the side aisles (where it is resolved into and supported by a vertical external buttress, rising from the ground).

The Notre Dame Cathedral (France) is the official seat of the Archbishop of Paris. Its architecture is one of the first examples of the use of flying buttresses, and the cathedral features numerous statues and stained glass windows. The original flying buttresses represented a structural innovation that would become central to the future development of Gothic architecture.