The basic repeating sequence in collagen consists of:
Gly-X-Y accurately describes the structural composition or molecular organization asked about in this question. In Protein, knowledge of molecular structure is directly linked to understanding biological function. The specific arrangement of chemical components in Gly-X-Y determines its physical properties, biological activity, and interactions with other molecules. The other options (Ala-Pro-Gly, Ser-Thr-Arg, and Leu-Lys-Val) describe different structural arrangements, incorrect stoichiometry, or compositions of different biological molecules.
Ref: Lehninger Principles of Biochemistry, Nelson & Cox, 8th Ed., Ch. 4