Final answer:
Glucagon is the hormone that maintains blood glucose levels during fasting by stimulating glycogenolysis and gluconeogenesis in the liver. Therefore, the correct option is 2.
Step-by-step explanation:
The hormone responsible for maintaining blood glucose levels during periods of fasting from food is glucagon. When blood glucose levels fall, the alpha cells of the pancreas secrete glucagon. Glucagon plays a crucial role in blood glucose homeostasis by stimulating the liver to convert glycogen back into glucose, a process known as glycogenolysis, and by promoting gluconeogenesis, which is the production of glucose from non-carbohydrate substrates.