**Core Concept**
Familial adenomatous polyposis (FAP) is a hereditary disorder caused by mutations in the APC gene, leading to development of numerous colorectal adenomatous polyps, high risk of colorectal cancer, and extraintestinal manifestations. It follows an autosomal dominant inheritance pattern, not recessive.

**Why the Correct Answer is Right**
FAP is caused by mutations in the *adenomatous polyposis coli (APC)* gene, which is inherited in an **autosomal dominant** manner. This means only one mutated copy of the gene is sufficient to cause the disorder. The presence of more than 100 colorectal polyps (often hundreds), duodenal polyps, and extra-intestinal features like desmoids or osteomas are hallmark clinical features. The inheritance pattern is consistently autosomal dominant, making **autosomal recessive** incorrect.

**Why Each Wrong Option is Incorrect**
Option B: More than 100 polyps in the colorectal area is a classic feature of FAP and is accurate.
Option C: Duodenal polyps are common in FAP, especially in the duodenum, and are a key diagnostic clue.
Option D: Extra-intestinal manifestations such as desmoid tumors, hepatoblastoma, and dental abnormalities are well-documented in FAP patients.

**Clinical Pearl / High-Yield Fact**
Remember: FAP is **autosomal dominant**, not recessive. A key exam trap is confusing it with other polyposis syndromes like Lynch syndrome (which is autosomal dominant too), or hereditary non-polyposis colorectal cancer (HNPCC), which is also dominant. Always confirm inheritance pattern — recessive is a red flag for this question.

✓ Correct Answer: A. Autosomal recessive transmission