The blood sugar concentration in an animal`s body, despite a carbohydrate-rich diet, tends to remain relatively constant due to the hormones of pancreas. This is reflected in option 2, which is the correct answer.

To elaborate, the pancreas secretes insulin and glucagon hormones which play a major role in regulating blood glucose levels. Insulin enables cells to absorb glucose and convert it into energy, decreasing blood glucose levels. On the other hand, glucagon stimulates the conversion of stored glycogen in the liver into glucose when blood sugar levels are low, thus increasing the glucose concentration in the bloodstream.

Option 1 is incorrect as hormones of pituitary gland mainly control growth and reproduction. Option 3 is not entirely correct as the liver does store glucose, but it`s the pancreas` hormones that enable this process. Option 4 is incorrect as autolysis refers to the self-digestion of cells, not the process of maintaining glucose balance.