The model in which the requirements are implemented by its category is

Explanation

In the evolutionary development model the requirements are first grouped into categories (typically by priority or by functional area) and then each category is designed, built and delivered as a separate evolution, with user feedback on one release shaping the next. The waterfall model implements the whole requirement set in one straight sequential pass, so no categorisation is involved. The prototype model builds a quick, usually throwaway, model to clarify requirements rather than to deliver them category by category. The official key marks the evolutionary development model, option 1.