Chromatography is used to analyse four dyes, P, Q, R and S. The solvent is water. The chromatogram obtained is shown below. Which statement concerning the dyes is correct?
- AAll four dyes are impure.
- BThe four dyes contain a total of eight different substances.
- CDye R is a mixture of dye P and dye Q.
- DDye S is a mixture of dye Q and one other substance.