PATHOLOGY

Detailed explanation-1: -The trachea contains ciliated pseudostratified columnar epithelium-lined tubular structures supported by rings of hyaline cartilage . The cartilage rings present in the trachea are c-shaped because the trachea passes through the esophagus. The rings prevent collapsing in the absence of air.

Detailed explanation-2: -A layer of hyaline cartilage supporting the tracheal rings surrounds the submucosa. The hyaline cartilage layer is sturdy but flexible and prevents the collapse of the trachea during expiration.

Detailed explanation-3: -Option D, as the Cartilaginous rings provide the structural support which the trachea requires to stay firm and strong and not to collapse during respiration. Hence, the correct answer is option (D). Note: When the trachea is affected due to some viral infection or illness it can result in coughing.