What defines a hypotonic solution in terms of osmolarity?

A hypotonic solution is defined as one that has a lower osmolarity compared to another solution, typically a hypertonic or isotonic solution. This lower osmolarity means that the hypothonic solution has a higher concentration of water relative to solutes. As a result, when cells are placed in a hypotonic solution, water moves into the cells by osmosis, which can lead to cell swelling and potentially bursting. This characteristic is what distinguishes hypotonic solutions from others, particularly when considering their effects on cellular environments.

The focus on low osmolarity and high water concentration in the correct answer captures the essence of what a hypotonic solution is, as it ultimately affects how cells interact with their surrounding fluid environments. Understanding this concept is crucial in fields like biology and medicine, especially regarding fluid balance and cell physiology.