In a science article about why alternating bands appear in a cave mineral deposit, two explanations are presented. One group favors the annual-wet-dry model, which attributes the pattern chiefly to seasonal changes in drip water chemistry making one band per year and would predict that bands should match annual cycles in rainfall and drip rate. Another group favors the flood-pulse model, which attributes the pattern chiefly to occasional storms depositing unusual minerals during brief high-flow events and would predict that bands should align with flood layers rather than every calendar year. The evidence is mixed rather than one-sided: investigators found that modern deposits formed paired light-dark layers each year, and they also found that thick bands matched mud left by known floods. The author concludes that both models use water chemistry but differ about regular seasons versus rare events. Which choice best compares the assumptions behind the two models?