Presence of cartilaginous rings in respiratory tract sct as: A. Support B. Keep passage open C. Prevent collapsing D. All of the above 💾 Save the Page as PDF: 📥𝐃𝐨𝐰𝐧𝐥𝐨𝐚𝐝 𝐍𝐨𝐰! Related Read more articles Previous PostThe distribution of air into lungs is controlled by: Next PostMajor contribution in inhalation by: If the aforementioned Answer is Wrong. Leave a Reply with an authentic source.Cancel reply