Task: Class Definition Understanding (ontology: Sciences/Biology)

Which of the following definitions best describes 'collagen type XX trimer'?

A. A collagen homotrimer of alpha1(XX) chains.
B. A collagen homotrimer of alpha1(XII) chains; type XII collagen triple helices may link sheet-forming or fibrillar collagens to other structures.
C. A collagen homotrimer of alpha1(XXI) chains; type XXI collagen triple helices found in the extracellular matrix component of blood vessel walls and in the cytoplasm of cultured human aortic smooth muscle.
D. A collagen homotrimer of alpha1(XXII) chains; type XXII collagen triple helices acts as a cell adhesion ligand for skin epithelial cells and fibroblasts.

Answer: A collagen homotrimer of alpha1(XX) chains.