Which of the following organisms can prepare their own food by Photosynthesis?

Photosynthesis requires chlorophyll, which captures light energy to convert carbon dioxide and water into glucose. Algae contain chlorophyll and are autotrophic, preparing their own food through photosynthesis. Fungi lack chlorophyll and are saprophytes. Rhizobium is a nitrogen-fixing bacterium that lives symbiotically in legume root nodules and does not perform photosynthesis. Viruses are non-cellular and cannot perform any metabolic activity outside a host. Hence algae is the correct answer.