What are the cells surrounding the stomata called?
a guard cells
b. mesophyll cells
oc palisade cells

The cells surrounding the stomata called Guard cells.

Option A

Explanation:  

The guard cells which are able to surround stomata. The transpiration happens in them with opening and closing process of stomata. A stomata is a spore found on the epidermal part of the leaves. Guard cells are specialized and very important cell. The pore is then see a boundary with specialized pore around it so that guard cell can deal with pore formation. The guard cells are largest while dealing with stomata. Whenever water enters the guard cells it tends to enhance the effect of water transpiration.