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
The annual conversion rate to dementia in patients with mild congnitive impairment is - 
Select and explain. 
A. 10%, B. 20%, C. 30%, D. 40%
A: 10%
Answer: A: 10% 
Explanation: None