Plant Kingdom

Answer (a) Starch

Most algae are photoautotrophic because they require only carbon dioxide as their primary source of energy and biomass.

Complete Answer:

For a wide and varied community of photosynthetic eukaryotic species, Algaeis an informal name. It is a polyphyletic grouping, containing species from different classes. Organisms range from single-cell microalgae, like diatoms and chlorella, to multicellular forms, like the giant kelp (massive brown algae that can develop up to 50m in length.)

Now, let us find the solution from the options-

• In nature, algae may either be autotrophic or heterotrophic. Other external organic compounds, including energy sources and carbon, are needed for chemoheterotrophic algae. 
• Starch, Floridian starch, oils, laminarin, soluble carbohydrates, paramylon, and chrysolaminarin are the reserved food materials found in algae.
• Glycogen acts as one of two sources of energy stores, with short-term glycogen and the other type of long-term storage of triglycerides in adipose tissue. Thus, option B is not the correct option.
• The sort of real grass whose stem is utilized is sugar cane, as it has a huge amount of sugar in it.
• Fats, along with proteins and carbohydrates, are among the three major macronutrient groups in the human diet. Thus, option D is not the correct option.

Thus, the correct answer is option (A) Starch.

Note: As algae do not have a shared ancestor, algae form a polyphyletic group and while their plastids appear to get a single origin, they were obtained in various ways from Cyanobacteria.