Which of the following is a prokaryotic organism that performs photosynthesis?

The correct answer is Cyanobacteria because this group of prokaryotic organisms is known for its ability to perform photosynthesis. Cyanobacteria, often referred to as blue-green algae, contain chlorophyll and other pigments that allow them to capture sunlight and convert it into chemical energy through the process of photosynthesis, producing oxygen as a byproduct.

In contrast, fungi, animals, and plants represent different domains of life. Fungi are eukaryotic and do not perform photosynthesis; instead, they obtain nutrients through absorption. Animals, also eukaryotic, rely on consuming other organisms for energy and are not capable of photosynthesis. While plants are eukaryotic organisms that do perform photosynthesis, they are distinctly different from prokaryotic organisms like Cyanobacteria. Therefore, among the given choices, Cyanobacteria is the only prokaryotic organism that carries out photosynthesis.