True about MHC-class –
**Core Concept**
The Major Histocompatibility Complex (**MHC**) plays a crucial role in the immune system, particularly in the presentation of antigens to T-cells. **MHC-class I** is expressed on the surface of almost all nucleated cells and is involved in presenting endogenously synthesized peptides to **CD8+ T-cells**.
**Why the Correct Answer is Right**
Since the specific details of the correct answer are not provided, a general explanation of **MHC-class I** is given. **MHC-class I** molecules are composed of an alpha chain and a beta-2 microglobulin chain. They present peptides from proteins produced inside the cell, such as viral proteins, to **CD8+ T-cells**, which then trigger cell death if the cell is infected.
**Why Each Wrong Option is Incorrect**
**Option A:** Without specifics, it's hard to address, but generally, incorrect options might misstate the function or expression pattern of **MHC-class I**.
**Option B:** Similarly, without details, but typically, this might incorrectly attribute **MHC-class II** functions to **MHC-class I**.
**Option C:** This could potentially misidentify the types of cells that express **MHC-class I** or the nature of antigens presented.
**Option D:** Might confuse **MHC-class I** with other immune functions or molecules.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that **MHC-class I** deficiency can lead to immune dysfunction, and its proper function is critical for the elimination of virally infected cells and tumor cells by the immune system.
**Correct Answer:** Not provided in the query.