Assessment Multiple Choice. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. Oxygen was scarce during the early development of Earth. By this situation, what kind of organism first existed? A. aerobic organisin B. anaerobic organism C. mammal D. protist 2. Which of the following statements is NOT true on the evolution of multicellular organisms? A. The process of continuous specialization brought more complex organisms. B. The prokaryotic organisms that formed multicellular aggregates were like the cells of Cyanobacteria. C. They are believed to have evolved from single-celled prokaryotic organisms. D. They are formed from other multicellular colonial aggregates through cells specialization. 3. Why do you think the emergence of plants and animals came later than simple living organisms? A. The cell structures of these multicellular organisms are more complex. 15​