**Core Concept**
The question is testing the student's knowledge of the immune response in the context of organ transplantation. The underlying principle is the recognition of foreign antigens by the immune system, leading to a rejection response. In transplantation, the major histocompatibility complex (MHC) antigens are of particular importance, as they are recognized as foreign by the recipient's immune system.

**Why the Correct Answer is Right**
The correct antigen involved in post-transplant rejection is the human leukocyte antigen (HLA) class I molecule, specifically HLA-A, HLA-B, and HLA-C. These MHC class I molecules are expressed on the surface of almost all nucleated cells and are recognized by CD8+ T cells, which are responsible for cell-mediated immunity. When a transplanted organ expresses these HLA molecules, the recipient's immune system may recognize them as foreign and mount an immune response against them, leading to rejection.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is likely a distractor, as there is no well-known antigen involved in post-transplant rejection that matches this description.

**Option B:** This option is incorrect, as HLA-DP and HLA-DQ are MHC class II molecules, which are primarily involved in the presentation of antigens to CD4+ T cells, rather than cell-mediated immunity.

**Option C:** This option is incorrect, as HLA-E, HLA-F, and HLA-G are MHC class I molecules, but they are not primarily involved in cell-mediated immunity and are not the primary antigens recognized in post-transplant rejection.

**Clinical Pearl / High-Yield Fact**
To remember the key antigens involved in post-transplant rejection, recall the "ABC" of HLA: HLA-A, HLA-B, and HLA-C are the major MHC class I molecules recognized by the immune system in transplantation.

**Correct Answer: C. HLA-A, HLA-B, and HLA-C**