Which of the following molecular movements is due to diffusion or osmosis? a) the sodium-potassium pump pumps three sodium ions out of a neuron for every two potassium ions it pumps in. b) when a plant cell is placed in concentrated salt water, water moves out of the cell. c)cells of the pancreas secrete insulin into the bloodstream.

The correct answer is  b) When a plant cell is placed in concentrated salt water, water moves out of the cell.

Explanation:

Osmosis is the movement of solvent molecules from an area of less concentration of solute to high concentration of solute to equalize the concentration of both the side of the cell.

So water will move outside the cell when any cell will be placed in a concentrated salt water because the concentration of solute is high in salt water and low inside the cell.

Therefore when a plant cell is placed in salt water the osmosis of water takes place from inside to outside the cell. So the right answer is b.