19. A

Single-row: 10M rows × 3 SQL statements × 0.03ms = 900,000ms = 15 minutes. Multi-row (rowset 500): 10M/500 = 20,000 batches × 3 SQL statements × 0.03ms = 1,800ms = 1.8 seconds. But note: the UPDATE cannot be multi-row FETCH in this scenario (it's a positioned update per row), so the actual answer de