Answer:
Cell, tissue, and organ.
Explanation:
A cell is an obvious one because it makes up the tissue, and it is needed in order to form an organ. Meaning tissue and cell would have to be included. Tissues witch are made of many cells form an organ, and an organ would be the human stomach/digestive system. It can't be organ system because a stomach can't be a whole system including the heart and ect. It can't be organism because a stomach isn't enough organ systems to create an organism.
