**Core Concept**
DNA repair is the process by which cells maintain genome stability by correcting damage to their DNA. Defects in DNA repair mechanisms can lead to genetic instability, cancer, and other diseases.

**Why the Correct Answer is Right**
Xeroderma pigmentosum (XP) is a rare genetic disorder caused by mutations in DNA repair genes, specifically those involved in nucleotide excision repair (NER). Individuals with XP are highly sensitive to ultraviolet (UV) light, which causes DNA damage, and often develop skin cancers at a young age. The defective DNA repair mechanism in XP leads to the accumulation of UV-induced DNA damage, resulting in skin lesions and increased cancer risk.

**Why Each Wrong Option is Incorrect**
**Option A:** Fanconi anemia is a disorder of interstrand crosslink repair, not primarily associated with defective nucleotide excision repair.
**Option B:** Ataxia telangiectasia is a disorder of DNA double-strand break repair, but it is not primarily associated with defective nucleotide excision repair.
**Option C:** Bloom syndrome is a disorder of DNA replication and repair, but it is not primarily associated with defective nucleotide excision repair.

**Clinical Pearl / High-Yield Fact**
XP patients are highly sensitive to UV light, and even brief exposure can cause severe sunburn, blistering, and skin lesions.

**Correct Answer: C. Xeroderma pigmentosum**