**Core Concept**
Granulomas are organized collections of immune cells, primarily macrophages and lymphocytes, that form in response to chronic inflammation and infection. They are a hallmark of granulomatous disease, which can be caused by various pathogens, including bacteria, fungi, and parasites.

**Why the Correct Answer is Right**
Granulomas are a protective mechanism against pathogens that are difficult to eliminate, such as Mycobacterium tuberculosis, which causes tuberculosis. In this disease, granulomas form in the lungs and are composed of macrophages that have engulfed the bacteria, as well as lymphocytes that help to control the infection. The formation of granulomas is a key feature of granulomatous disease and is characterized by the presence of epithelioid cells, which are modified macrophages that have a distinctive appearance under the microscope.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because granulomas are indeed seen in sarcoidosis, a disease that is characterized by the formation of granulomas in various organs, including the lungs, lymph nodes, and skin.
**Option B:** This option is incorrect because granulomas are also seen in Crohn's disease, a type of inflammatory bowel disease that is characterized by chronic inflammation and granuloma formation in the gut.
**Option C:** This option is incorrect because granulomas are also seen in histoplasmosis, a fungal infection that is caused by the fungus Histoplasma capsulatum and is characterized by the formation of granulomas in the lungs.

**Clinical Pearl / High-Yield Fact**
It's worth noting that granulomas can be a feature of various diseases, including infections, autoimmune disorders, and malignancies. A high index of suspicion is necessary to diagnose granulomatous disease, and a biopsy of affected tissue may be necessary to confirm the diagnosis.

**Correct Answer: D.**