The diagrams below show models of the circulatory systems of a fish and a frog. A student compared these diagrams. The student found that each of these organisms had a heart to pump blood. Which statement is supported by the student's findings?

1. Some organisms are composed of one cell, which others are multicellular.
2. Many multi-cellular animals have similar organs and specialized systems.
3. The circulatory system in most organisms removes solid wastes from their bodies.
4. All animals have identical circulatory systems.