(B) Shrinkage of cytoplasm in hypertonic medium.
Plasmolysis in a plant cell is defined as shrinkage of cytoplasm in hypertonic medium. When a cell is immersed in hypertonic (very concentrated) solution, water diffuses out of the cell by the process of exosmosis. As a result, the cell shrinks. If exosmosis continues in a plant cell, the cytoplasm appears to be shrunken. This is called plasmolysis and the cell is said plasmolysed.