In the passage, the function of the highlighted portion is to A. provide specific examples of organisms whose longevity does not increase in response to calorie restriction. B. illustrate the probable means by which organisms placed on a calorie-restriction diet compensate for the reduction in available food-based level. C. suggest the mechanism that is responsible for prolonging the life of organism whose calorie intake is significantly reduced. D. give an example that explain why scientists' thinking about the physiological effects of calorie restriction changed. E. distinguish the different ways that mammalian and non-mammalian metabolisms respond to significant reductions in calorie intake