Mucus is made by the body as protection against disease. What kind of defence is stomach acid?
- Acells ✓, chemical barrier ✓, mechanical barrier ✓
- Bcells ✓, chemical barrier ✗, mechanical barrier ✗
- Ccells ✗, chemical barrier ✓, mechanical barrier ✗
- Dcells ✗, chemical barrier ✗, mechanical barrier ✓