Which of the following is a correct description of guard cell activity with regard to stoma? - When the guard cells become flaccid from losing water, the stoma opens.

-Each stoma is controlled by a single guard cell, which absorbs water to open the stoma and loses water to close the stoma.

-The activity of guard cells in opening and closing each stoma helps maintain a state of balance in the leaf that maximizes photosynthesis and minimizes transpiration.

-When the guard cells become turgid with absorbed water, the stoma closes and CO2 cannot enter. ​