Answer: a) Alzheimer’s disease
Step-by-step explanation:
Alzheimer is a kind of dementia disease. This disease is associated with the problems of memory, behavior and thinking. The symptoms of the disease appears slowly and get worse with the time. This disease interfere with recognizing people, remembering past events and other memory related problems. This disease can be commonly seen in old age people.
The given situation can be related with the symptoms of alzheimer's disease as Muriel faces trouble in recalling the names of the best friends.