Mannitol, a 5-carbon sugar, is able to cross the capillary endothelium in the systemic circulation but not in the cerebral circulation.

Mannitol, a 5-carbon sugar, is able to cross the capillary endothelium in the systemic circulation but not in the cerebral circulation. The ‘blood-brain-barrier’ prevents its movement into the cerebral interstitium. Furthermore, mannitol cannot enter any cells, i.e. it cannot be metabolized. A patient in a hospital receives an intravenous infusion of saline made slightly hyperosmotic with mannitol in order to treata) general edema in the whole body due to a weak heart,b) pulmonary edema due to the failure of the left heart to pump out what it receives from the lungs,c) cerebral edema due to a head injury,d) edema in the lower legs of an expecting mother.Briefly justify your answer: