An alga which can be employed as food for human beings:

Step-by-step solution

Chlorella is the green alga belonging to Chlorophyceae can be a nutritious food with many health benefits. It enhances the immune system, helps to improve the good cholesterol level, and acts as an antioxidant. It helps in keeping the blood pressure and blood glucose level under check. Helps in managing the respiratory diseases. Polysiphonia is a red alga. Spirogyra and Ulothrix are also Chlorophyceae members.