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
True about third heart sound is -a) Absent in Chr. constrictive pericariditisb) Absent in aortic aneurysmc) Absent in MSd) Normal physiologically in Athletes 
Select and explain. 
A. ab, B. bc, C. bd, D. cd
D: cd
Answer: D: cd 
Explanation: None