Which aquatic plant type is rooted in sediment and extends above the water surface?

The correct choice indicates that the aquatic plant type being referred to is emersed. Emersed plants are characterized by having their roots anchored in sediment while their shoots extend above the water surface. This positioning allows them to access both aquatic and aerial environments, with portions of the plant exposed to air, often aiding in processes like photosynthesis and respiration.

In contrast, rooted-floating plants remain anchored but their leaves and stems float on the water's surface rather than extending above it. Submersed plants, on the other hand, are entirely underwater, lacking any part that extends above the surface. Free-floating plants do not have any root system in the sediment; instead, they drift on the water's surface and are typically not anchored at all. Therefore, the unique characteristics of emersed plants make them the best fit for the description provided in the question.