Identify a marine alga that is used as food. 

Sargassum

The correct answer is Option (2) – Sargassum

Sargassum is a marine alga that is commonly used as food.

Explanation: Sargassum is a genus of brown macroalgae (seaweed) that is abundant in marine environments, particularly in tropical and subtropical regions. It is edible and has been used as food in various cultures around the world. Sargassum is rich in vitamins, minerals, and dietary fiber, making it a nutritious addition to diets. In some regions, it is consumed directly as a vegetable or used in soups, salads, and other dishes. Additionally, extracts of Sargassum are used in food products as thickeners, stabilizers, and flavor enhancers. Therefore, Sargassum serves as an important source of food and nutrition in coastal communities and is valued for its culinary and dietary benefits.