Which aquatic plant type is attached to sediment with leaves that float on the water surface?

The correct answer is rooted-floating. This type of aquatic plant is characterized by having a portion of its structure—specifically the roots—anchored to the sediment on the bottom of a water body, while its leaves float on the surface of the water. This adaptation allows the plant to access sunlight for photosynthesis while being anchored to a stable substrate in the sediment.

Rooted-floating plants, such as water lilies, exhibit this combination of features, which enables them to thrive in aquatic environments. The anchoring of the roots helps maintain their position in the water and provides stability against currents, while their floating leaves can efficiently absorb light and carbon dioxide from the atmosphere.

Free-floating plants do not have roots that anchor them to the sediment; they float freely on the water’s surface. Emersed plants grow above the water level, with most of their structure outside of the water, which distinguishes them from rooted-floating plants. Submersed plants are completely underwater and do not have any floating leaves, as they typically adapt to life beneath the water's surface. Each of these other types has its own ecological role, but rooted-floating plants specifically fulfill the criteria outlined in the question.