Answer:
4. organ system
Step-by-step explanation:
The human body is made up of several organs and systems, which work together to ensure the perfect functioning of the organism. If we look at the microscopic level, we can perceive the presence of thousands and thousands of cells, which form tissues, even more cells form organs and even more cells form systems, a characteristic that allows us to affirm that human beings are multicellular organisms.
The main systems of the organism are: Integumentary System, Skeletal System; Muscular System; Cardiovascular System, Respiratory System, Digestive System, among others.