Evaluate the effect of insulin on glycogen synthase activity. Which statement is correct?

• A. Insulin activates glycogen synthase by inhibiting GSK3 and stimulating protein phosphatase 1.
• B. Insulin inhibits glycogen synthase by activating GSK3.
• C. Insulin has no effect on glycogen synthase activity.
• D. Insulin activates glycogen synthase by inhibiting protein phosphatase 1.

Answer: (A)