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: Anaesthesia
True about endotracheal intubation is – 
Select and explain. 
A. It reduces normal anatomical dead space, B. It produces decrease in resistance to respiration, C. Subglottic edema is most common complication, D. All of the above
A: It reduces normal anatomical dead space
Answer: A: It reduces normal anatomical dead space 
Explanation: Intubation decreases the dead space, as nasal space is bypassed and the lumen of endotracheal tube is less than that of natural airway.
Endotracheal intubation increases the airway resistance.
Bronchial intubation is the most common perioperative complication and sore throat is the most common post operative complication.