Which aquatic plant is identifiable by its dark green leaves arranged in whorls and anchored in sediment?

The correct choice for identifying the aquatic plant with dark green leaves arranged in whorls and anchored in sediment is wild celery. Wild celery, also known scientifically as Vallisneria, typically has long, slender leaves that grow in a whorl pattern at the base, giving it a distinctive appearance. This plant is commonly found in freshwater environments and plays a crucial role in aquatic ecosystems by providing habitat for wildlife and stabilizing sediments.

Other options do not meet the description accurately. Sago pondweed has broader leaves that do not typically form whorls. Coontail, while having a bushy appearance, is more branched and does not have whorled leaves. Filamentous algae are not vascular plants and typically do not have leaves arranged in whorls but rather exist as tangled, filamentous structures. Understanding these characteristics is essential in identifying aquatic plants accurately within their respective habitats.