Figure: Paper chromatogram of a mixture and known dyes

The chromatogram shows spots from a mixture M and known dyes. Which conclusion is supported?
M is pure
M contains dyes P and R
M contains only dye Q
M is insoluble in the solvent
107 exam-style questions on Edexcel GCSE Chemistry 3.2 Methods of separating and purifying substances, covering 3.2.1 Pure substances and mixtures, 3.2.2 Techniques for separating mixtures, 3.2.3 Paper chromatography and Rf values, and 3.2.4 Making water potable. Each one has a worked solution and a mark scheme showing where the marks go.