Final answer:
Red blood cells are hemolyzed in a hypotonic solution, leading to the cells swelling and potentially rupturing due to an influx of water.
Step-by-step explanation:
Red blood cells are hemolyzed when the cells are placed in a hypotonic solution. In such an environment, water rushes into the cells because the external solution has a lower solute concentration compared to the inside of the cell. As a result, the red blood cells swell and can burst (lyse), which is not the case in an isotonic or hypertonic solution where they either retain their shape or shrink, respectively.