👍Correct option is B 😊📃guard cells swell up. When water enters in guard cells, this creates pressure on the wall and the guard cells swell up and due to swelling,👍 the stomatal pores open.📜✍️👍👍

Explanation:

Stomata are tiny pores present on the surface of leaves and stems of plants. They regulate the exchange of gases, i.e., carbon dioxide and oxygen, between the plant and the atmosphere. The opening and closing of stomata depend on the turgor pressure of the guard cells that surround the pore. When the guard cells accumulate water, they become turgid and swell up, causing the stomatal pore to open. Conversely, when the guard cells lose water, they become flaccid and shrink, causing the stomatal pore to close.

Reasons why Guard cells swell up:
Guard cells swell up due to the following reasons:

1. Accumulation of Potassium Ions - When the plant cell accumulates potassium ions, it lowers the water potential of the guard cells, leading to the influx of water through osmosis. This inflow of water causes the guard cells to swell up and bend apart, opening the stomatal pore.

2. Active Transport - Active transport of ions into the guard cells, such as potassium and chloride, creates a concentration gradient and causes water to enter the cells through osmosis. This osmotic entry of water causes the guard cells to swell up and open the stomatal pore.

3. Photosynthesis - During photosynthesis, the guard cells produce ATP, which is an energy source that drives the active transport of ions, leading to the accumulation of K+ ions in the guard cells. This accumulation of K+ ions causes the guard cells to swell and open the stomatal pore.

Conclusion:
Thus, the opening of stomatal pores is due to the swelling up of guard cells, which is caused by the accumulation of potassium ions, active transport, and photosynthesis.