The event which George Bush was referring to was the D. attack on the World Trade Center in 2001
This refers to the terrorist attack that was done at the World Trade Center which claimed many lives when a plane was hijacked and crashed into it.
Hence, we can see that the reference that was made by George Bush was about the 9/11 incident and now said that first responders won't be the ones fighting, but the military.
Read more about 9/11 here:
https://brainly.com/question/1082025
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