Which of the following is the movement of a pure solvent (liquid) across a membrane?

Choice A reason: This is incorrect because over-hydration is unlikely in a dehydrated patient. Over-hydration is a condition where the body has too much water, which can cause hyponatremia, edema, and cerebral swelling.

Choice B reason: This is incorrect because diarrhea is a cause, not a consequence, of dehydration. Diarrhea is the frequent and watery passage of stool, which can lead to fluid and electrolyte loss.

Choice C reason: This is incorrect because pulmonary congestion is also unlikely in a dehydrated patient. Pulmonary congestion is a condition where the lungs are filled with fluid, which can cause dyspnea, cough, and crackles.

Choice D reason: This is correct because fall is a potential complication of dehydration. Dehydration can cause confusion, dizziness, weakness, and hypotension, which can increase the risk of falling and injuring oneself.

Choice A reason: This is incorrect because polyuria is a sign of hyponatremia, not hypernatremia. Polyuria is the excessive production of urine, which can cause fluid loss and sodium dilution.

Choice B reason: This is correct because dry mucous membranes are a sign of hypernatremia. Dry mucous membranes are caused by dehydration, which can occur in hypernatremia due to fluid shifting from the intracellular to the extracellular space.

Choice C reason: This is incorrect because diarrhea is a sign of hyponatremia, not hypernatremia. Diarrhea is the frequent and watery passage of stool, which can cause fluid and electrolyte loss.

Choice D reason: This is incorrect because intense thirst is a sign of both hyponatremia and hypernatremia. Intense thirst is a result of the body's attempt to restore fluid balance and osmolarity.

Choice E reason: This is incorrect because vomiting is a sign of both hyponatremia and hypernatremia. Vomiting is a reflex action that expels the contents of the stomach, which can cause fluid and electrolyte loss or imbalance.