- Aspirin prevents platelet aggregation (coagulation) and inhibits prostaglandin synthesis. Both matches are correct.
- Histamine causes constriction (not dilation) of smooth muscle in the bronchi, leading to bronchoconstriction.
Therefore, option 2 is incorrect.
- Histamine stimulates secretion of gastric acid (HCl) in the stomach, so option 4 is correct.
Hence, the incorrect pair is "Histamine - dilates smooth muscle in bronchi."
Brass alloy is made of which metals?