**Core Concept**
Turcot's syndrome is a rare genetic disorder characterized by the association of primary brain tumors, usually glioblastoma or medulloblastoma, with multiple colorectal adenomas or carcinomas. It is a variant of familial adenomatous polyposis (FAP).

**Why the Correct Answer is Right**
Turcot's syndrome is primarily linked to mutations in the APC gene, which is the same gene responsible for FAP. This genetic mutation leads to the development of multiple adenomatous polyps in the colon, which may progress to colorectal cancer. The brain tumors in Turcot's syndrome are thought to arise from the same genetic defect, resulting in the formation of malignant gliomas or medulloblastomas.

**Why Each Wrong Option is Incorrect**
* **Option A:** Duodenal polyps are not a characteristic feature of Turcot's syndrome.
* **Option B:** Familial adenomatous polyposis (FAP) is actually the underlying condition for Turcot's syndrome, rather than a separate entity.
* **Option C:** While brain tumors are a key feature of Turcot's syndrome, they are not the only possible association.
* **Option D:** Villous adenomas are a type of polyp, but they are not specifically associated with Turcot's syndrome.
* **Option E:** Hyperplastic polyps are not typically associated with Turcot's syndrome.

**Clinical Pearl / High-Yield Fact**
Turcot's syndrome highlights the importance of genetic counseling and surveillance in families with a history of FAP or other hereditary colorectal cancer syndromes.

**Correct Answer: B. Familial adenomatous polyposis**