X-Chromosome Inactivation in Female Mammals Occurs Mostly Randomly Early in Development

X-chromosome inactivation in female mammals occurs mostly randomly early in development, resulting in a heterogeneous cell population, with each cell having inactivated one or the other of its X chromosomes and passing on the same X-inactivation choice to its offspring. The inactivated X chromosome is generally hypermethylated and transcriptionally inactive. You are studying a newly discovered type of colon tumor in women that has a morphology distinct from that of other colon adenomas. You extract chromosomal DNA from the tumor cells. You then either keep the DNA untreated, or digest the DNA with a methylation-sensitive restriction enzyme that only cleaves its recognition DNA sequence if the sequence is not methylated. Finally, you amplify by polymerase chain reaction (PCR) a locus on the X chromosome known to be polymorphic in length (i.e. it is expected to be of different sizes in different X chromosomes). The locus has a restriction site for the mentioned enzyme, such that cleavage would prevent PCR amplification. You quantify the amount of PCR products corresponding to shorter and longer versions of the locus, and obtain the results shown in the following table. Do these data appear to be in better agreement with a monoclonal (M) or a polyclonal (P) origin of cancer? A monoclonal origin would mean that all cells in the tumor are the clonal descendants of a single abnormal cell, while a polyclonal tumor is composed of cells from different lineages. Write M or P as your answer.