Final answer:
Cells placed in a solution of pure water will undergo hemolysis, where they swell up with water and burst.
Step-by-step explanation:
When cells are placed in a solution of pure water, the water concentration outside the cells is higher than inside the cells. As a result, water molecules will move into the cells through osmosis, leading to the swelling and eventually bursting of the cells. This process is called hemolysis, which is the correct answer choice (a).