**Core Concept**
The **Human Leukocyte Antigen (HLA) system** is a part of the immune system and is crucial for the body's defense against pathogens. **HLA class I** molecules are involved in presenting endogenously synthesized peptides to **CD8+ T cells**. They are expressed on the surface of almost all nucleated cells.

**Why the Correct Answer is Right**
HLA-I molecules are expressed on the surface of nearly all nucleated cells, as they present peptides from inside the cell to the immune system, helping to identify and destroy infected cells or tumor cells. This widespread expression is crucial for the immune system's ability to survey the body's cells for signs of infection or malignancy. The presentation of peptides by HLA-I to CD8+ T cells is a key step in cell-mediated immunity.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because while HLA-I is indeed present on many types of cells, the correct answer choice is not provided here to assess.
**Option B:** Incorrect for the same reason as Option A, lacking the specific details needed to evaluate its correctness.
**Option C:** Similarly, without the specific details of this option, it cannot be deemed correct or incorrect based on the information given.
**Option D:** Also incorrect due to the lack of specific details to assess its accuracy.

**Clinical Pearl / High-Yield Fact**
A key point to remember is that HLA-I is expressed on almost all nucleated cells, which is vital for the immune system to recognize and destroy infected cells or tumor cells. This fact is crucial in understanding transplant rejection and autoimmune diseases.

**Correct Answer:** Correct Answer: D. All nucleated cells.