**Core Concept:** Celiac sprue is an autoimmune disorder where ingestion of gluten triggers an immune response leading to damage of the small intestine and malabsorption.

**Why the Correct Answer is Right:** The correct answer is "D," as wheat is the cereal that should be avoided in celiac sprue patients. This is due to the presence of gluten, a protein found in wheat, barley, and rye, which triggers the immune response in celiac sprue patients.

**Why Each Wrong Option is Incorrect:**

A. Rice is a staple food in many cultures and is gluten-free, making it the wrong choice for celiac sprue patients.
B. Corn is another food source that celiac sprue patients should avoid due to the presence of gluten, but it is not the correct answer as rice is better suited for these patients.
C. Soy is a plant-based protein and does not contain gluten, making it an incorrect option for patients with celiac sprue.

**Clinical Pearl / High-Yield Fact:** Highlighting the importance of following a gluten-free diet in celiac sprue patients can help prevent complications such as malnutrition, anemia, and osteoporosis, and improve overall health outcomes.

**Correct Answer:** D. Rice