Answer:
The best answer choice from the options offered in the lists, would be the third one: Red blood cell, heart tissue, circulatory system.
Step-by-step explanation:
Although the red blood cell is not the least complex unit that forms either the heart, or the circulatory system, the question asks to choose the list that shows organization in the human body from the least complex of living units, to the most complex. Definetly, the cell is the least complex of all the human units, and it is the very basis of all the organs and systems. Next in complexity, and formed by a series of cells, is the tissue, which then join together, with other organs, to form the most complex of all units, the circulatory system. The red blood cell, the heart tissue, join together to become active parts in the largest of all units, the circulatory system. This option is the one that offers an organization from least complex to more complex.