Which of the following statements is correct? A) Fluids and solutes can be transported out of a cell via pinocytosis. B) A hypertonic solution has an osmotic pressure that is greater than the intracellular fluid of a red blood cell. C) Bulk flow involves the movement of fluids and solutes down a concentration gradient. D) In secondary active transport ATP is used to move a solute down its concentration gradient. E) During osmosis, water moves from an area of high osmotic pressure to an area of low osmotic pressure.

The correct answer is **B) A hypertonic solution has an osmotic pressure that is greater than the intracellular fluid of a red blood cell.**<br /><br />Here's why:<br /><br />* **A) Fluids and solutes can be transported out of a cell via pinocytosis.** Pinocytosis is a form of endocytosis, which brings fluids and solutes *into* a cell, not out. Exocytosis transports materials out of a cell.<br /><br />* **C) Bulk flow involves the movement of fluids and solutes down a concentration gradient.** Bulk flow refers to the movement of fluids and solutes together due to a pressure gradient, not a concentration gradient. Think of blood moving through vessels – that's bulk flow driven by blood pressure.<br /><br />* **D) In secondary active transport ATP is used to move a solute down its concentration gradient.** Secondary active transport uses the energy stored in an electrochemical gradient created by primary active transport (which *does* use ATP directly). Secondary active transport itself doesn't directly use ATP and often moves a solute *against* its concentration gradient.<br /><br />* **E) During osmosis, water moves from an area of high osmotic pressure to an area of low osmotic pressure.** Osmosis is the movement of water across a selectively permeable membrane from an area of *low* osmotic pressure (higher water concentration) to an area of *high* osmotic pressure (lower water concentration). Water moves to dilute the area with more solutes.<br /><br />* **B) A hypertonic solution has an osmotic pressure that is greater than the intracellular fluid of a red blood cell.** This is the correct statement. A hypertonic solution has a higher concentration of solutes compared to the inside of the red blood cell. This creates a higher osmotic pressure outside the cell, drawing water out of the cell and potentially causing it to shrink or crenate.<br />