**Core Concept**
Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by inflammation and joint destruction. The pathogenesis of RA involves a complex interplay between genetic and environmental factors, with certain HLA alleles playing a crucial role in predisposing individuals to the disease. The association between HLA and RA is a classic example of a genetic predisposition to an autoimmune disease.

**Why the Correct Answer is Right**
The correct answer is HLA-DRB1, specifically the shared epitope alleles (e.g., HLA-DRB1*0401 and HLA-DRB1*0404). These alleles are strongly associated with RA and are thought to contribute to the disease through the presentation of self-peptides to autoreactive T cells, leading to an autoimmune response. The HLA-DRB1 molecule is a class II MHC protein that plays a critical role in antigen presentation to CD4+ T cells, and the shared epitope alleles are thought to alter the conformation of the HLA-DRB1 molecule, leading to the presentation of autoantigens to autoreactive T cells.

**Why Each Wrong Option is Incorrect**
* **Option A:** HLA-B27 is associated with ankylosing spondylitis, a different autoimmune disease characterized by inflammation of the spine and other joints. While HLA-B27 is a major genetic risk factor for ankylosing spondylitis, it is not associated with RA.
* **Option B:** HLA-DQ is a class II MHC protein that is involved in antigen presentation, but it is not as strongly associated with RA as HLA-DRB1. HLA-DQ alleles may contribute to the risk of developing RA, but they are not the primary genetic risk factor.
* **Option D:** HLA-C is a class I MHC protein that is involved in antigen presentation, but it is not associated with RA. HLA-C alleles are not thought to contribute to the risk of developing RA.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that the association between HLA and RA is complex and influenced by multiple genetic and environmental factors. While HLA-DRB1 is a major genetic risk factor for RA, other genetic and environmental factors also contribute to the development of the disease.

**Correct Answer:** C.