Nicole feels she will not forget the emotions she felt upon hearing of the attacks on America on September 11th. She remembers very vividly what she was doing, who she was with, what was said, and what emotions she experienced. Nicole has?

Post traumatic stress disorder

it is diagnosable after months of having more than one symptoms of PTSD, including flashbacks, nightmares, etc. if she had it short-term and it went away, it would be acute stress disorder. since it is years after the event, it is PTSD