The belief that many government officials had that the levees in new orleans would protect it from the devastating flood waters of hurricane katrina represent which symptom of groupthink?

The belief that many government officials had that the levees in New Orleans would protect it from the devastating flood waters of hurricane Katrina represent
the illusion of invulnerability, as a symptom of groupthink.
Illusion of invulnerability describes situation in which group members ignore danger, they are overly optimistic and take extreme risk.

The answer is "illusion of invulnerability".

Groupthink expects people to abstain from raising disputable issues or elective arrangements, and there is loss of individual innovativeness, uniqueness and independent reasoning. The dysfunctional  gathering flow of the "ingroup" creates a "illusion of invulnerability"  (an expanded assurance that the correct choice has been made). In this way the "ingroup" essentially misrepresents its own particular capacities in basic leadership and altogether underrates the capacities of its adversaries (the "outgroup"). Besides, groupthink can create dehumanizing activities against the "outgroup".