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
According to CDC, past smoker is 
Select and explain. 
A. Person who had smoked >100 cigarettes previously and is not smoking currently, B. Person who has smoked >10 cigarettes previously and is not smoking currently, C. Person who has smoked >100 cigarettes previously and  reduces to 10 cigarettes per day, D. Person who has smoked > 100 cigarettes in his or her lifetime, who smokes now, but does not smoke every day
A: Person who had smoked >100 cigarettes previously and is not smoking currently
Answer: A: Person who had smoked >100 cigarettes previously and is not smoking currently 
Explanation: None