Step 1: The task. Match each stage of the cell cycle to the activity that happens in it.
Step 2: First match. Item I is the S-phase, which pairs with D, DNA duplication. In this phase the DNA is copied. So I-D.
Step 3: Second match. Item II is prophase, which pairs with A, the start of spindle assembly. So II-A.
Step 4: Third match. Item III is the quiescent stage (G0), which pairs with B, an active but non-dividing state where the cell does its normal work. So III-B.
Step 5: Fourth match. Item IV is metaphase, which pairs with C, chromosomes lining up at the equator of the cell. So IV-C.
Step 6: Conclusion. The matches are I-D, II-A, III-B, IV-C. Therefore the correct answer is "I-D, II-A, III-B, IV-C". \[ \\boxed{\\text{I-D, II-A, III-B, IV-C}} \]
