Final answer:
The concentration of the solution is >0.40 molar.
Step-by-step explanation:
The concentration of the solution is a. >0.40 molar. When a cell is placed in a solution with a higher concentration of solute particles, the water will move out of the cell in an effort to equalize the osmolality. This will cause the cell to shrink, rather than increase in volume. Therefore, the solution must have a higher concentration than the osmolality of the cell, which is 0.40 osmolal of NaCl.