The claim of the "other commentators" suggests that they believe which of the following about Notre-Dame? A. It was the inspiration for many vaulted cathedrals built in the thirteenth and fourteenth centuries. B. Its design flaws were not apparent until flying buttresses were added in the thirteenth or fourteenth century. C. Its flying buttresses are embellished with decoration characteristic of the thirteenth and fourteenth centuries. D. It had been modified in some respects before flying buttresses were added in the thirteenth or fourteenth century. E. It was originally constructed in an architectural style that was considered outmoded by the thirteenth or fourteenth century.