**Core Concept**
Major Histocompatibility Complex (MHC) molecules play a crucial role in the immune system by presenting peptides from pathogens to T-cells, thereby initiating an immune response. MHC molecules are expressed on the surface of antigen-presenting cells (APCs) such as dendritic cells and macrophages.

**Why the Correct Answer is Right**
MHC class I molecules present endogenously synthesized peptides to CD8+ T-cells, while MHC class II molecules present exogenously derived peptides to CD4+ T-cells. This distinction is essential for the proper functioning of the immune system, as it allows for the recognition and elimination of infected cells or foreign substances. The MHC complex is encoded by a cluster of genes on chromosome 6 in humans, and variations in these genes can affect the immune response to pathogens.

**Why Each Wrong Option is Incorrect**
**Option A:** This option might be incorrect if it contradicts the role of MHC molecules in presenting peptides to T-cells.
**Option B:** This option might be incorrect if it suggests that MHC molecules are not involved in the immune response.
**Option C:** This option might be incorrect if it implies that MHC molecules are not expressed on the surface of APCs.

**Clinical Pearl / High-Yield Fact**
A key clinical application of MHC molecules is in transplantation medicine, where matching the MHC types of the donor and recipient can significantly reduce the risk of graft rejection.

**Correct Answer:** C.