Eugene drew the following diagram to describe the levels of structural organization of an animal’s body. He will list the cell as both the least specialized and the most numerous at the bottom of the pyramid. Which of the following should he list in level 1 on the diagram? (Hint: Step 1. List the levels of cellular organization in animals. Step 2. Arrange the levels of organization from least specialized and highest in number to most specialized and lowest in number. Step 3. Identify the level of organization that would fall at the top of the pyramid.)