**Core Concept**
Gluten-sensitive enteropathy, also known as celiac disease, is a chronic autoimmune disorder primarily affecting the small intestine. It is triggered by an adverse reaction to gluten, a protein found in wheat, barley, and rye. This condition leads to inflammation, mucosal damage, and malabsorption of essential nutrients.

**Why the Correct Answer is Right**
The correct answer is linked to the autoimmune nature of gluten-sensitive enteropathy. Celiac disease is characterized by the presence of circulating autoantibodies, specifically tissue transglutaminase antibodies (tTGA), which play a crucial role in the disease's pathogenesis. The immune system mistakenly targets the gluten protein, leading to an inflammatory response and damage to the intestinal mucosa. This process is mediated by the activation of T cells, which recognize gluten as a foreign antigen.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because selective IgA deficiency is a condition where individuals have low levels of IgA antibodies, but it is not directly associated with gluten-sensitive enteropathy.
**Option B:** This option is incorrect because Crohn's disease is a type of inflammatory bowel disease (IBD) that affects the gastrointestinal tract, but it is not primarily caused by an immune reaction to gluten.
**Option C:** This option is incorrect because ulcerative colitis is another type of IBD that affects the colon, but it is not directly related to gluten sensitivity.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that celiac disease can manifest with a wide range of symptoms, including diarrhea, abdominal pain, fatigue, and weight loss. However, some patients may be asymptomatic, and the condition is often diagnosed incidentally during endoscopy or biopsy for unrelated reasons.

**Correct Answer:** D