This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Larynx, Subject name: ENT
Which of the following is true regarding congenital subglottic stenosis? 
Select and explain. 
A. Diagnosed if subglottic diameter is less than 4mm in full term neonate, B. Diagnosed if subglottic diameter is less than 3mm in premature neonate, C. Cry is normal, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Congenital subglottic stenosis It is due to abnormal thickening of cricoid cailage or fibrous tissue seen below the vocal cords. Child may remain asymptomatic till upper respiratory infection causes dyspnoea and stridor. Cry is normal as in laryngomalacia. Diagnosis:- Diagnosis is made when subglottic diameter is less than 4 mm in full-term neonate (normal 4.5-5.5 mm) or 3 mm in premature neonate (normal 3.5 mm). Many cases of congenital stenosis improve as the larynx grows but some may require surgery. Ref:- Dhingra; pg num:-295