Here's a problem to solve: Insulin is an important protein for the regulation of glucose levels in the blood. Which statement best describes the function of insulin?

Among the 4 following options, which is the correct answer?

- A: Insulin stimulates cells to absorb glucose from the blood.
 
- B: Insulin causes the liver to release glucose into the blood.
 
- C: Insulin facilitates the effects of antibiotics in the cell.
 
- D: Insulin develops chemical bonds on the cell membrane.
 