Arrange the following chlorine compounds in ascending order of their typical concentration used in water chlorination:
1. Sodium hypochlorite in drinking water
2. Chlorine bleach in shock chlorination
3. Calcium hypochlorite in swimming pools
4. Trihalomethanes (by-products of chlorination)
1
4, 3, 1, 2
2
1, 3, 2, 4
3
2, 1, 4, 3
4
4, 2, 3, 1