In guard cells when sugar is converted into starch, the stomatal pore

Explanation

The correct answer is that the stomatal pore closes completely when sugar is converted into starch in guard cells. This conversion decreases the osmotic potential, causing water to exit the cells and leading to a loss of turgor pressure. As a result, the guard cells become flaccid and the stomatal pore closes, preventing gas exchange and water loss. The other options are incorrect because they fail to account for the osmotic changes and resulting turgor pressure reduction that cause the stomatal closure.