## Core Concept
C-C beta chemokines are a subgroup of chemokines characterized by the presence of two adjacent cysteine residues separated by one non-cysteine amino acid (C-C motif). They play a crucial role in the recruitment of various immune cells, such as monocytes, T cells, and eosinophils, to sites of inflammation.

## Why the Correct Answer is Right
The correct answer, **C. RANTES (CCL5)**, is a member of the C-C chemokine family. RANTES (Regulated on Activation, Normal T Cell Expressed and Secreted) is known to attract T cells, eosinophils, and basophils, and is involved in inflammatory responses. It is officially designated as CCL5. This chemokine acts through CCR1, CCR3, and CCR5 receptors.

## Why Each Wrong Option is Incorrect
- **Option A:** IL-8 (Interleukin-8) is a C-X-C chemokine, not a C-C chemokine. It primarily attracts neutrophils and plays a key role in acute inflammatory responses.
- **Option B:** MCP-1 (Monocyte Chemoattractant Protein-1) is indeed a C-C chemokine, officially known as CCL2. While it is correct that MCP-1 is a C-C chemokine, the question seems to seek an option that might not fit or is less representative. MCP-1 primarily attracts monocytes and basophils.
- **Option D:** SDF-1 (Stromal cell-Derived Factor 1) is a C-X-C chemokine, officially known as CXCL12. It primarily acts through the CXCR4 receptor and is involved in chemotaxis and homing of cells, including stem cells.

## Clinical Pearl / High-Yield Fact
A key point to remember is that chemokines and their receptors play critical roles in the trafficking of immune cells and have implications in various diseases, including inflammatory disorders, autoimmune diseases, and cancer. RANTES/CCL5, specifically, has been implicated in several inflammatory and infectious diseases due to its broad range of target cells.

## Correct Answer Line
**Correct Answer: C. RANTES (CCL5)**