This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Physiology
Conducting zone of the respiratory system is: 
Select and explain. 
A. 1st generation of airways, B. 0th generation to 16th generation of airways, C. 0th generation to 23rd generation of airways, D. 16th to 23rd generation of airways
B: 0th generation to 16th generation of airways
Answer: B: 0th generation to 16th generation of airways 
Explanation: Of the 23 generations, trachea is considered as 0th generation, and trachea and first 16 generations are called "conducting zone". Last 7 generations are called "respiratory zone"; gas exchange occurs in these generations. The gas exchange areas include respiratory bronchioles and alveoli.