**Core Concept**
Familial adenomatous polyposis (FAP) is a genetic disorder characterized by the development of hundreds to thousands of polyps in the colon and rectum, leading to a high risk of colorectal cancer. This condition is inherited in an autosomal dominant pattern and is caused by mutations in the APC gene.

**Why the Correct Answer is Right**
The APC gene, located on chromosome 5q21-22, acts as a tumor suppressor by regulating cell division and preventing the uncontrolled growth of cells. Mutations in the APC gene lead to the accumulation of beta-catenin, a protein that promotes cell proliferation and survival. This, in turn, results in the formation of adenomatous polyps in the colon, which can progress to colorectal cancer if left untreated.

**Why Each Wrong Option is Incorrect**
**Option A:** Chromosome 7 is associated with other genetic disorders, such as Fanconi anemia, but not FAP.

**Option B:** Chromosome 18 is linked to other types of cancer, including gastric cancer, but not FAP.

**Option C:** Chromosome 11 is associated with other genetic disorders, such as WAGR syndrome, but not FAP.

**Clinical Pearl / High-Yield Fact**
FAP is a classic example of a tumor suppressor gene mutation leading to cancer. Remember the " APC" gene and its association with familial adenomatous polyposis (FAP) when considering genetic predispositions to colorectal cancer.

**Correct Answer: D. Chromosome 5.**