A 5-year-old Caucasian male is brought to your genetics clinic. His past medical history is significant for diffuse erythema, scaling, and freckle-like areas of increased pigmentation over areas of...

A 5-year-old Caucasian male is brought to your genetics clinic. His past medical history is significant for diffuse erythema, scaling, and freckle-like areas of increased pigmentation over areas of his body after sunlight exposure. You diagnose him with xeroderma pigmentosum and explain to the mother that it is a hereditary condition resulting in uncorrected DNA mutations that may lead to skin cancer due to what type of defective gene?

 A. Apoptotic gene

 B. Proto-oncogene

 C. Tumor suppressor

 D. DNA repair gene