**Core Concept**
Diffuse specific lesions on intestinal biopsy reflect distinct pathological patterns linked to immune-mediated or metabolic disorders. These lesions are characterized by tissue-specific immune responses or malabsorption syndromes, with histological findings varying by disease etiology.

**Why the Correct Answer is Right**
- **Whipple’s disease (b)**: Causes diffuse, lamellar, and granular lesions in the small intestine due to *Tropheryma whipplei* infection, leading to malabsorption and villous atrophy.
- **Abetalipoproteinemia (d)**: Results in diffuse, fatty, and fibrotic changes in the intestinal mucosa due to defective apolipoprotein B synthesis, impairing fat absorption.
- **Agammaglobulinemia (c)**: Features diffuse lymphoid depletion and absence of B cells, leading to recurrent infections and non-specific intestinal inflammation, though not a classic "lesion" pattern. However, chronic inflammation and villous atrophy can occur.
- **Celiac sprue (a)**: Shows **crypt hyperplasia** and **villous atrophy**, but the lesions are **not diffuse-specific**—they are focal and reactive, not due to a specific infectious or metabolic agent.

**Why Each Wrong Option is Incorrect**
Option A: Celiac sprue has villous atrophy and crypt hyperplasia, but these are **reactive**, not **diffuse specific lesions**; thus, it does not fit the "diffuse specific" criterion.
Option C: Agammaglobulinemia presents with immune deficiency, not a characteristic diffuse intestinal lesion pattern.
Option D: Abetalipoproteinemia causes diffuse fatty infiltration, but it is not the most typical for "specific diffuse lesions" compared to Whipple’s.

**Clinical Pearl / High-Yield Fact**
Whipple’s disease and abetalipoproteinemia both show **diffuse, specific intestinal histological changes** with no reactive villous atrophy—key to distinguishing them from celiac disease. Always check for **infectious or metabolic causes** when diffuse lesions are seen.

✓ Correct Answer: B. bcd