Step 1: Understanding the instruments and parameters.
- Tintometer is used for measuring the colour, so it corresponds to parameter (II).
- Nephelometer measures turbidity, hence corresponds to parameter (III).
- Imhoff cone is used to measure settleable solids, which corresponds to (IV).
- Muffle furnace is used for measuring volatile solids, hence it corresponds to (I).
Step 2: Conclusion.
Based on the analysis, the correct matching is (A) - (II), (B) - (III), (C) - (IV), (D) - (I).
Final Answer:
\[
\boxed{4. (A) - (II), (B) - (III), (C) - (IV), (D) - (I)}
\]