The most complex of the component units of the human body. An organization of varying numbers and kinds of organs so arranged that together they can perform complex functions for the body. A. System B. Cells C. Tissues D. Organ Clear selection

. System<br /><br />Systems are composed of organs, which are in turn composed of tissues, which are made up of cells. The coordinated function of multiple organs in a system allows for complex processes like digestion, respiration, or circulation, making the system the most complex unit listed.<br />