This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
An 80 year old man has a history of progressive gait disturbance and incontinence which had been attributed to old age and prostatism. For the past 4 months he has been forgetful and confused. He has a history of head trauma 25 years ago. His head CT is shown below .The most likely diagnosis 
Select and explain. 
A. Alzheimer’s disease, B. Creutzfeldt – jakob disease, C. Normal pressure hydrocephalu, D. Pelizaeus-merzbacher disease
C: Normal pressure hydrocephalu
Answer: C: Normal pressure hydrocephalu 
Explanation: Normal pressure hydrocephalus triad:

Dementia
Ataxia
Incontinence

CT or MRI brain in these patients shows enlarged frontal and temporal horns of lateral ventricles out of proportion to degree of cortical atrophy.