Consider the following structures: 1. Respiratory tract epithelium 2. Gastrointestinal tract epithelium 3. Urogenital tract epithelium 4. Skin 5. Stomach lining Mucus coating acts as a barrier in which of the above?
- A1, 2 and 3 only
- B1, 2, 3 and 4 only
- C2, 3, 4 and 5 only
- D1, 3, 4 and 5 only
✓ Correct answer: A
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