Which of the following statements correctly describes the main secondary structural feature of collagen?

• A. The main secondary structure feature of collagen is a simple α-helix.
• B. The main secondary structure feature of collagen is a unique triple helix.
• C. The main secondary structure feature of collagen is a simple β-pleated sheet.
• D. The main secondary structure feature of collagen are both α-helix and β-pleated sheet.

Answer: (B)