The correct answer is Cell, tissue, organ, and system
Step-by-step explanation:
The smallest unit of each living organism is the cell as this structure is essential for functions such as reproducing, obtaining nutrients from food, among others. Indeed, cells are considered as the building blocks of life. Moreover, in multicellular organisms, cells organize into more complex structures called tissues that contain cells with similar features that have the same function. For example, the nervous tissue transmits, processes and receives stimulus or information.
Besides this, tissue groups to form organs; for example, nervous tissue forms the brain that process, receives and sends information, control other organs, among others. Finally, organs form organ systems; for example, the brain, spinal cord, nerves, etc. are part of the nervous system. According to this from the lowest to the highest or more complex degree of internal organization, the order is cell, tissue, organ, and system.