Water is cleaned by passing it through a series of stages. Four stages are shown below. 1. Chlorine is introduced into the water to destroy any bacteria. 2. The water is run through coarse gravel so that large bits of dirt are removed. 3. The water is run through wire screens so that large twigs are removed. 4. The water is run through fine sand so that small particles are removed. What is the correct sequence for carrying out these stages?
- A$1 \rightarrow 2 \rightarrow 3 \rightarrow 4$
- B$2 \rightarrow 1 \rightarrow 4 \rightarrow 3$
- C$3 \rightarrow 2 \rightarrow 4 \rightarrow 1$
- D$4 \rightarrow 3 \rightarrow 2 \rightarrow 1$