What architectural element of the choir at the abbey church of saint-denis was introduced at the time of abbot suger's redesign?

The choir at the abbey church of saint-denis demonstrates Gothic architecture. When Abbot Suger redesigned the choir, he purportedly built the first building showing features of Gothic architecture. This then became a model and inspiration for many medieval cathedrals and buildings. The church is currently a major architectural landmark in the basilica form.