Respiratory tract histology identification

Steps:

• Examine epithelium: Respiratory passages feature pseudostratified ciliated columnar epithelium with goblet cells, not squamous; squamous appears in alveoli.
• Check for smooth muscle: Present in bronchi and bronchioles, but visibility depends on section.
• Identify cartilage: Bronchi contain cartilage rings; bronchioles lack cartilage entirely.
• Evaluate statements: Statement 1 incorrect due to wrong epithelium type; statement 2 may not match image; statement 3 correct as cartilage rules out bronchioles.

Why D is correct:

• Bronchioles are defined by absence of cartilage, so visible cartilage confirms the section is from a bronchus, not a bronchiole.

Why the others are wrong:

• A: Includes false statements 1 and 2.
• B: Includes false statement 1.
• C: Includes false statement 2.

Final answer: D