In Females,all the Cells in a Tumor Have the Same

In females,all the cells in a tumor have the same inactive X chromosome.The reason for this is that:

A) all of the cells in a tumor are derived from a single progenitor cell.
B) all late-stage tumors have chromosome abnormalities.
C) multiple mutations are required for tumor induction.
D) many tumor-suppressor genes are on the X chromosome.