A cell is put in sat water and it's size decreases. Which of the following best explain what happened?

Plasmolysis

Explanation:

Plasmolysis is the shrinking of cell when it is put in hypertonic environment, i. e. with high salt concentration.

When the cell environment has low water concentration (or high salt concentration) with respect to the cell, water from the cell diffuses out into the environment, thus causing the cell to shrink