Compound C is used in textile and leather processing. On gentle heating with a few drops of concentrated sulfuric acid, which starting material(s) produce compound C?
- A$\text{CH}_3\text{COOH}$ only
- B$\text{HOCH}_2\text{COOH}$ only
- C$\text{CH}_3\text{COOCH}_2\text{COOH}$ only
- D$\text{CH}_3\text{COOH}$ mixed with $\text{HOCH}_2\text{COOH}$