The answer is b) hypotonic.
Explanation: A solution is termed hypotonic if it has a lower concentration of solutes compared to another solution. In the case of 100 percent distilled water, it contains no solutes, making it less concentrated than the solution inside the cells, which contains various solutes such as salts, sugars, and proteins. When a cell is placed in a hypotonic solution, water moves into the cell by osmosis in an attempt to equalize the solute concentrations on both sides of the cell membrane. This can lead to the cell swelling and potentially bursting if too much water enters.