Answer:
D. systems, termed as "organ system".
Step-by-step explanation:
The organ system is a system that consists of a group of organs that work together to ensure that the organism continues to survive.
Tissues are next in creating the specific organs, and are generally classified depending on the organ it is part of. Note that not all tissues are the same.
Cells are "the smallest", and groups of cells create tissues.
Nerves are part of the Nervous system, which helps provide sensory to the body to help react when the body comes into contact with something that may hurt body parts.
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