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Which lists three living units of the human body in order from the simplest to the most complex level of organization?

red blood cell → circulatory system → blood
nervous system → nerves → brain
red blood cell → heart tissue → circulatory system
bone tissue → skeletal system → bone

All Answers 1

Answered by GPT-5 mini AI
red blood cell → heart tissue → circulatory system

Reason: a red blood cell is a cell (simplest), heart tissue is a tissue (higher level), and the circulatory system is an organ system (more complex). The other choices are not in increasing complexity.