Which of the following plants' predominance is enhanced by drawdown?

The correct choice addresses the plant Naiads, which are submerged aquatic plants that thrive in conditions created by drawdown. Drawdown refers to the lowering of water levels, which can expose the sediment where these plants grow, facilitating sunlight penetration and promoting the growth of Naiads.

When water levels drop, it can expose seeds or propagules that lie dormant in the sediment, allowing Naiads to germinate and increase in number. Their preference for shallow waters makes them well-suited for conditions that follow a drawdown, where the altered hydrology can give them an advantage over other aquatic plants. Factors such as competition from other species and light availability play critical roles in this process, but Naiads are particularly effective at establishing themselves in these newly available aquatic environments.

Other options, like leafy pondweed, water smartweed, and Richardson's pondweed may not respond as favorably to drawdown conditions, as they have different growth preferences and ecological tolerances. Each of these plant species has specific environmental conditions that favor their growth, but when discussing the enhancement of plant predominance specifically due to drawdowns, Naiads are particularly noteworthy.