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

Choice A reason: This is correct because 3.5 to 5.0 mEq/L is the normal range of serum potassium level in adults. Potassium is an electrolyte that is important for nerve and muscle function, as well as acid-base balance.

Choice B reason: This is incorrect because 8.5 to 10.5 mg/dL is the normal range of serum calcium level in adults, not potassium. Calcium is an electrolyte that is involved in bone health, muscle contraction, and blood clotting.

Choice C reason: This is incorrect because 135 to 145 mEq/L is the normal range of serum sodium level in adults, not potassium. Sodium is an electrolyte that is essential for fluid balance, nerve transmission, and muscle contraction.

Choice D reason: This is incorrect because 1.8 to 2.6 mEq/L is the normal range of serum magnesium level in adults, not potassium. Magnesium is an electrolyte that is important for muscle and nerve function, as well as enzyme activity.

Choice A reason: This is correct because prolonged bed rest can cause hypocalcemia, or low serum calcium level. Calcium is stored in the bones and is released into the blood when the bones are stressed by weight-bearing activities. When a person is on bed rest, the bones are not stimulated and the calcium remains in the bones, leading to a decrease in serum calcium level.

Choice B reason: This is incorrect because too much butter consumption does not affect the serum calcium level directly. Butter is a source of fat and calories, which can affect the cholesterol and triglyceride levels, but not the calcium level. However, too much butter consumption can cause obesity, which can increase the risk of osteoporosis and fractures.

Choice C reason: This is incorrect because hyperparathyroidism can cause hypercalcemia, or high serum calcium level. Hyperparathyroidism is a condition where the parathyroid glands produce too much parathyroid hormone (PTH), which regulates the calcium and phosphorus balance in the body. PTH stimulates the release of calcium from the bones into the blood, leading to an increase in serum calcium level.

Choice D reason: This is incorrect because excessive ingestion of vitamin D can also cause hypercalcemia, or high serum calcium level. Vitamin D is a fat-soluble vitamin that helps the body absorb calcium from the food and supplements. When a person takes too much vitamin D, the calcium absorption is increased and the serum calcium level rises.