What type of organism uses cilia for locomotion?

Cilia are hair-like structures that extend from the surface of certain eukaryotic cells and serve various functions, primarily locomotion and feeding. Organisms such as Paramecium, Vorticella, and Stentor utilize cilia to move through their aquatic environments. These protists are single-celled organisms that exhibit a form of locomotion known as ciliary movement, which allows them to navigate through water by coordinating the beating of numerous cilia in a wave-like manner.

In contrast, bacteria are prokaryotic organisms that may move using flagella, not cilia, and their mechanisms are quite different from those of eukaryotic organisms. Algae, while they may be motile, generally use flagella for movement rather than cilia, depending on the type of algae. Fungi, on the other hand, do not have structures like cilia for locomotion; they primarily grow through mycelium and do not exhibit fluid movement.

Thus, the organisms that use cilia for locomotion are specifically those noted, making that the correct choice.