**Core Concept**
The MHC (Major Histocompatibility Complex) class I complex is a crucial component of the immune system, responsible for presenting endogenously synthesized peptides to CD8+ T cells. This process is essential for the recognition and elimination of infected cells or tumor cells.

**Why the Correct Answer is Right**
The MHC class I complex consists of a heavy chain (α chain) and a light chain (β2-microglobulin), which forms the peptide-binding groove. This groove is responsible for binding and presenting peptides derived from endogenously synthesized proteins to CD8+ T cells. The correct answer is related to the heavy chain of the MHC class I complex, as it forms the component that interacts with the antigen-presenting cell and the T-cell receptor.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the β2-microglobulin is a light chain that associates with the α chain, but it is not the component that forms the antigen-presenting part.
**Option B:** Incorrect because the CD8 coreceptor is essential for the interaction between the T-cell receptor and the MHC class I complex, but it is not a component of the MHC complex itself.
**Option C:** Incorrect because the peptide-binding groove is formed by the α chain, but it is not the correct answer as it is not the component that forms the antigen-presenting part.

**Clinical Pearl / High-Yield Fact**
The MHC class I complex plays a critical role in the recognition of infected cells or tumor cells by CD8+ T cells. Understanding the structure and function of the MHC class I complex is essential for the development of effective immunotherapies and vaccines.

**Correct Answer:** C.