How is the prevention of futile cycles achieved in glycogen metabolism?

• A. By activating both glycogen phosphorylase and glycogen synthase simultaneously.
• B. By regulating the phosphorylation state of glycogen phosphorylase and glycogen synthase to ensure only one is active at a time.
• C. By increasing the concentration of glucose in the cell.
• D. By inhibiting both enzymes simultaneously.

Answer: (B)