What is the largest level of structural organization of the human body?

The correct answer is "organism" because it represents the highest level of biological complexity in the human body. An organism is a complete living entity capable of performing all the basic life processes, including growth, reproduction, and homeostasis. In the context of human anatomy, this level of organization encompasses all other levels: cells make up tissues, tissues form organs, and organs work together in organ systems. Each of these lower levels contributes to the overall function and maintenance of the organism, but it is the organism itself that is the end result of these organizational levels. Understanding this hierarchy is key in anatomy and physiology as it underscores how complex structures and functions emerge from simpler components working together.