Nijmegen breakage syndrome is a human disease that is characterized by immunodeficiency, cancer predisposition, and microcephaly. It is a disorder that is caused by the inheritance of two mutant copies of a gene called NBS1, whose product is involved in DNA repair. Knowing this, what does this tell you about the relationship between DNA repair processes and the immune system?

A. DNA repair processes must be critical for the proper functioning of the immune system, as when they are nonfunctional, the immune system does not function properly.
B. The NBS1 gene must have multiple alleles, one that affects DNA repair, and one that affects the immune system.
C. Nijmegen breakage syndrome is caused by an epistasis relationship between a gene affecting DNA repair and a gene affecting the immune system.
D. Nothing. Nijmegen breakage syndrome is the result of polygenic inheritance, and therefore the immunodeficiency seen in these patients is due to the inheritance of another gene.