The correct answer is: A. Spongilla
Spongilla is a genus of freshwater sponges. It is the type genus of the family Spongillidae. The common name “pond silk” is used to refer to some species of Spongilla.
Sponges are simple animals that lack a true body plan. They are made up of a network of cells that are connected by a jelly-like substance. Sponges filter food particles from the water using their cells.
Spongilla are found in freshwater habitats around the world. They are often found in ponds, lakes, and streams. Some species of Spongilla can also be found in marine habitats.
Sponges are an important part of the aquatic ecosystem. They provide food and shelter for other animals. They also help to filter the water and remove pollutants.
Here is a brief description of each option:
- A. Spongilla is a genus of freshwater sponges. It is the type genus of the family Spongillidae. The common name “pond silk” is used to refer to some species of Spongilla.
- B. Chlorella is a genus of green algae. It is a unicellular organism that is found in freshwater and marine habitats. Chlorella is a photosynthetic organism, which means that it can produce its own food using sunlight.
- C. Selaginella is a genus of plants that is found in tropical and subtropical regions. It is a member of the Lycopodiaceae family. Selaginella is a small plant that has a creeping stem. It produces small, cone-like structures that contain spores.
- D. Spirogyra is a genus of green algae. It is a filamentous organism that is found in freshwater habitats. Spirogyra is a photosynthetic organism, which means that it can produce its own food using sunlight.