Structural features of terminal bronchioles

Steps:

• Locate terminal bronchioles as the last conducting airways before alveoli.
• Note cartilage provides partial structural support in their walls.
• Recognize simple cuboidal epithelium lacks cilia for mucus transport.
• Identify smooth muscle enables diameter control for airflow.

Why C is correct:

• Terminal bronchioles contain cartilage and smooth muscle but no cilia, per standard respiratory anatomy defining their role in conduction without ciliary clearance.

Why the others are wrong:

• A: Smooth muscle is present, not absent.
• B: Cartilage is present, not absent.
• D: Both cilia absent and smooth muscle present contradict the row.

Final answer: C