Anatomical Features of Bronchioles

Steps:

• Define bronchioles as small airways (<1 mm diameter) distal to bronchi, lacking cartilage and glands.
• Evaluate statement 1: All bronchioles lack cartilage, true for structural support via elastic fibers.
• Evaluate statement 2: Bronchioles do not contain cartilage rings, unlike larger bronchi, so false.
• Evaluate statement 3: All bronchioles have surrounding smooth muscle for airflow regulation, true.

Why B is correct:

• B identifies statements 1 and 3, matching the defining lack of cartilage and presence of smooth muscle in all bronchioles.

Why the others are wrong:

• A includes false statement 2 about cartilage presence.
• C selects only false statement 2.
• D omits true statement 1 on cartilage absence.

Final answer: B