T Cells Binding to MHC Class I-Peptide Complexes Are Responsible

T cells binding to MHC class I-peptide complexes are responsible for acceptance or rejection of transplanted organs. To facilitate acceptance of the transplant, the ideal donor will have a close genetic relationship with the recipient -- even then, immune suppression drugs are often necessary. In a strange variation of this phenomenon, the endangered Tasmanian devil of Australia suffers from a devastating disease in which tumorous tissue is transmitted from animal to animal. What is the likely explanation for the lack of rejection of this transmissable tumor?

A) Tumors are never targeted by T cells, unless they are caused by a viral infection.
B) Tasmanian devils lack an adaptive immune system.
C) Inbreeding in the small population has led to reduced genetic diversity and much-less variable MHC class I genes.
D) MHC class I genes are unique to humans. Without them, the T cells have no way to distinguish self and non-self.