Blood glucose level is regulated by two antagonistic hormones, glucagon and insulin. The following graph shows the fluctuations in an individual's blood glucose level over a five hour period: <image 1>. From the information provided above and your knowledge of physiology, which of the following statements are appropriate? I. Normal homeostatic mechanisms maintain a glucose concentration of approximately 1 mg/ml. II. Glucagon is released at points A and C. III. The individual eats a meal at point D. IV. Insulin is being released at points B and E.
['I only', 'I and II only', 'I and IV only', 'I, II, and III only', 'II, III, and IV only']