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: ENT
All are true about Laryngomalacia except -a) Most common congenital anomaly of larynxb) Stridor disappear on supine positionc) Manifest many weeks after birth d) It needs no treatment in most of the cases 
Select and explain. 
A. a, B. c, C. ac, D. bc
D: bc
Answer: D: bc 
Explanation: None