Which of the following dipeptides and tripeptides are correctly paired with their corresponding 1-letter abbreviations?
I. Arg-Ser: R-S
II. Glu-Asn-Gly: Q-N-G
III. Pro-Asp-Tyr: P-D-Y
IV. Met-Lys: M-L
V. Leu-Cys-Val: L-C-V