Answer:
dissociative amnesia
Explanation:
Dissociative amnesia may be defined as a medical condition where n individual is not able to remember some of the important information about his or her life. The brain goes blank abut what has happened to them and could not recall any information.
When a person cannot remember any information form a certain period of time, it is then called as localized dissociative amnesia.
In the context, Alison went missing for three weeks and when found she could not remember where she was for the last three weeks and what happened to her. She is suffering from localized dissociative amnesia as she could recall what happened to her for the last three weeks. She only remembers walking by the lake. Thus this shows the condition of dissociative amnesia.