According to the "people and the environment" section about lessons learned from hurricane katrina,

The answer is "It is not clear whether New Orleans is protected from all sizes of hurricanes".
Hurricane Katrina was massively dangerous and destructive tropical typhoon that was the costliest cataclysmic event and one of the five deadliest hurricanes in the historical backdrop of the United States. It was the third significant hurricane of the record-breaking 2005 Atlantic hurricane season.

i would say b. research typically uses a variety of sources