Cyanobacteria are also known as A. Autotrophic bacteria B. Blue Green Algae C. Red Brown Algae D. None of the above

The correct answer is A. Autotrophic bacteria.

Cyanobacteria are a type of bacteria that are able to photosynthesize, meaning they can use sunlight to create their own food. This makes them autotrophic, or self-feeding. Cyanobacteria are also known as blue-green algae, but they are not true algae. They are more closely related to bacteria than to algae.

Red brown algae are a type of algae that are found in marine environments. They are photosynthetic and have a red or brown color. Red brown algae are not closely related to cyanobacteria.

None of the above is not the correct answer.