They work to maintain and to support the conditions that your cells, tissues, and organs need to function properly.
Water evaporates and comes down as rain thats how the water cycle works and the carbon cycle works by oxygen being turned into carbon by humans and animals breathing and trees convert carbon back into oxygen so the cycle goes on and on
friend typed this in he is sitting next to me
Hey there!
The purpose of guard cells is to control the opening and closing of the Stomata, keeping it the correct width, or size.
Therefore, your correct answer would be Option 3, control the size of the Stomata.
Hope this helps!