**Core Concept**
Peutz-Jegher syndrome is a rare autosomal dominant disorder characterized by pigmented macules on the lips and oral mucosa, and the presence of gastrointestinal hamartomatous polyps, particularly in the small intestine. It is associated with increased risk of gastrointestinal and breast cancers.

**Why the Correct Answer is Right**
Peutz-Jegher syndrome presents with characteristic blue-gray pigmentation of the lips and oral mucosa, and patients develop multiple hamartomatous intestinal polyps, most commonly in the small bowel. The condition is caused by mutations in the *STK11* gene, leading to dysregulation of cell growth and apoptosis. The familial pattern in this case—both Lalita and her sister having the same features—strongly supports a hereditary syndrome. The clinical triad of pigmentation, intestinal polyps, and cancer predisposition is highly specific for this diagnosis.

**Why Each Wrong Option is Incorrect**
Option A: Carcinoid tumor is a neuroendocrine tumor, typically arising from enterochromaffin cells, and presents with flushing, diarrhea, or carcinoid syndrome, not pigmentation or intestinal polyps.
Option B: Melanoma is a malignant skin cancer originating from melanocytes, not associated with oral pigmentation or intestinal polyps.
Option C: Villous adenoma is a type of colorectal polyp, usually seen in colorectal cancer risk, but does not cause oral pigmentation or have a familial pattern of pigmented lesions.

**Clinical Pearl / High-Yield Fact**
Remember: "Pigment + Polyps + Family history = Peutz-Jegher syndrome." Always consider this in patients with oral pigmentation and gastrointestinal polyps, especially in a family setting.

✓ Correct Answer: D. Peutz-Jegher syndrome