This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Organic Mental Disorders, Subject name: Psychiatry
Cause of organic amnestic syndrome include(s): a. Multiple sclerosis b. Hypoglycemia c. Hyperglycemia d. Hypoxia e. Hypercapnia 
Select and explain. 
A. all of the above, B. a,b,e, C. a,b,d, D. b,c,d
C: a,b,d
Answer: C: a,b,d 
Explanation: Amnestic syndrome is characterized by inability to form new memories (anterograde amnesia) and the inability to recall previously remembered knowledge (retrograde amnesia). The major causes of amnestic disorders are: Thiamine deficiency (Korsakoff syndrome) Hypoglycemia Primary brain conditions(head trauma,seizures,cerebral tumors, cerebrovascular disease, hypoxia, electroconvulsive therapy, multiple sclerosis) Substance related disorders (alcohol, benzodiazepines).