**Core Concept**
The collagen triple helix structure is a distinctive arrangement of amino acid chains, comprising two alpha-1 chains and one alpha-2 chain, held together by hydrogen bonds. This unique structure provides the tensile strength and elasticity characteristic of collagen fibers found in connective tissue.

**Why the Correct Answer is Right**
Collagen is a major protein component of the extracellular matrix and is essential for tissue structure and function. The triple helix structure of collagen is stabilized by hydrogen bonds between the amino acid chains, specifically between the glycine residues and the imino acid residues proline and hydroxyproline. This specific arrangement of amino acids is crucial for the formation of collagen fibers.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because collagen is indeed found in skin, where it provides elasticity and tensile strength. The triple helix structure of collagen is responsible for these properties.
**Option B:** Incorrect because collagen is a major component of bone matrix, where it provides tensile strength and helps to regulate bone mineralization.
**Option C:** Incorrect because collagen is also found in tendons, where it provides elasticity and tensile strength, allowing for the transmission of forces across joints.

**Clinical Pearl / High-Yield Fact**
Collagen fibers are the primary component of scar tissue, which is formed in response to tissue injury. The triple helix structure of collagen is essential for the formation of strong, stable scar tissue.

**Correct Answer: D. Basement Membrane**