Homeostasis is achieved primarily through the ability of cells to maintain internal stability. This involves various processes and mechanisms that regulate the internal environment of an organism, ensuring that conditions remain relatively constant despite external changes. While the secretion of enzymes and the control of movements (both voluntary and involuntary) can play roles in maintaining homeostasis, the central concept is the regulation and stabilization of internal conditions by cells.
Thus, the most accurate response is:
Cells maintain internal stability.