Answer:
4. Similarity
Step-by-step explanation:
Cell is the structure on which humans exist. They perform all the functions of life like reproduction,movement, responding to changes in the environment they find themselves, growth, excretion, etc. All living organisms have cells in them and they perform similar functions.
The main function of cell in living organisms is conversion of food nutrients into energy thereby providing structure for the body. Without cell, organisms cannot exist hence it is termed basic unit of life.
Although they are small and trillions found in living organisms yet they are important to the survival of organisms.