Final answer:
A red blood cell that swells and eventually undergoes hemolysis is placed in a hypotonic solution. This solution has a lower concentration of solutes compared to the inside of the cell, causing water to enter the cell and leading to its rupture. so, option 2 is the correct answer.
Step-by-step explanation:
When a red blood cell is placed in a solution and it begins to swell and undergo hemolysis, the solution is referred to as a hypotonic solution. In a hypotonic solution, the concentration of solutes outside the red blood cell is lower than inside the cell, which causes water to rush into the cell due to osmosis. This influx of water can lead to the cell swelling and eventually rupturing, which is also known as hemolysis.
An isotonic solution is one where the amount of solutes in the solution equals that inside the cell, maintaining equilibrium and the cell's shape. Conversely, in a hypertonic solution, the solute concentration is higher outside the cell than inside, leading to water moving out of the cell and the cell shrinking, a process known as crenation.