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: Unknown
The post-operative quality of life (QOL) scores of 200 prostate cancer patients has a mean of 60 and a standard deviation of 10. How many patients are expected to have a QOL score between 40 and 80? 
Select and explain. 
A. 190, B. 136, C. 120, D. 140
A: 190
Answer: A: 190 
Explanation: The values enclosed in a normal distribution curve are: