When potassium ion is transported into guard cells, water: a) enters by osmosis. b) is actively transported out of the cells. c) moves to the edge of the cell. d) leaves by osmosis. e) is actively transported into the cells.

Enters by osmosis.
Explanation: The active transport of potassium ions into guard cells creates an osmotic gradient, causing water to enter the cells by osmosis, leading to increased turgor pressure and the opening of the stomata.