When large amounts of nitrates are carried into rivers, these changes may happen and fish may die. 1. Water plants die and sink to the river bed. 2. Bacteria increase very quickly. 3. The concentration of oxygen in the water falls. 4. More single-celled water plants grow, turning the water green. In what sequence do these changes happen?
- A$1 \rightarrow 4 \rightarrow 3 \rightarrow 2$
- B$2 \rightarrow 3 \rightarrow 1 \rightarrow 4$
- C$3 \rightarrow 2 \rightarrow 4 \rightarrow 1$
- D$4 \rightarrow 1 \rightarrow 2 \rightarrow 3$