Correct Answer: Guard cells

Solution : The correct option is Guard cells.

Each stomatal pore is encircled by two guard cells, which are specialised epidermal cells. These cells regulate the stomatal pore's opening and closure. When guard cells absorb water, they become turgid and open the stomata. The stomata shut as they lose water and become flaccid. This system allows plants to change the size of their stomata in response to environmental stimuli such as light, humidity, and water. Dicots has kidney-bean shaped guard cells while monocots has dumb-bell shaped cells.