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
Position for orotracheal intubation – 
Select and explain. 
A. Extension of neck and atlanto-occipital joint, B. Extension of only neck, C. Flexion of neck only, D. Flexion of neck and extension of atlanto-occipital joint
D: Flexion of neck and extension of atlanto-occipital joint
Answer: D: Flexion of neck and extension of atlanto-occipital joint 
Explanation: Optimal head neck for ET intubation is obtained by flexion of the neck and extension of the atlanto-occipital joint.