Which of these would be a protozoan form of life? *

1)a large, complex organism -- such as a human whose body is made of multiple organ systems.
2)a tiny organism that was one of the first to develop and whose body is a single cell.
3)a large, complex organism that converts solar energy into chemical energy.
4()any organism that takes in (or breathes in) oxygen and puts out CO2 (carbon dioxide)