Final answer:
Distressing memory flashbacks and nightmares are most closely associated with Post-traumatic stress disorder (PTSD).
Step-by-step explanation:
Distressing memory flashbacks and nightmares are most closely associated with Post-traumatic stress disorder (PTSD). PTSD is an anxiety disorder that occurs after experiencing severe psychological trauma. Individuals with PTSD often experience intrusive thoughts, memories, and nightmares related to the traumatic event.