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
All are true regarding bronchial cyst, EXCEPTa) 50-70% are seen in lungb) Usually seen in mediastinumc) May be premalignantd) Commonly gets infected 
Select and explain. 
A. a, B. bc, C. ad, D. ac
D: ac
Answer: D: ac 
Explanation: None