What significant change took place in the abbey church of saint-denis?
a.
the tower was changed.
b.
the stained glass windows were replaced with new ones.
c.
three portals were added to the western facade.
d.
all of the above

Option C.

Explanation:

Three portals were added to the western facade, is the right answer.

In the city of Saint-Denis, the Basilica of Saint-Denis is a magnificent abbey church of the medieval period. This church has a significant place in the architectures of the period due to the fact that it was the primary structure to be built in the Gothic style. This church is a great cruciform structure of "basilica" style; that is, it has a central core with more profound passages and clerestory windows. The significant changes in the structure of the church can be observed in the Three portals that were added to the western facade.

the answers is b.   environments.