Stomatal pores do not open in response to an increase in sugar content, but rather, they close.- Option A is incorrect 

Stomata pores close when there's a decrease in the osmotic concentration (solute concentration) of the guard cells, leading to water loss and shrinking of the guard cells.- Option B is incorrect 

Stomatal pores typically do not open in response to a decrease in sugar content (specifically sucrose) in mesophyll cells; rather, they tend to close.- Option C is incorrect

 An increase in sugar content (specifically, from mesophyll cells) in the guard cells can indeed lead to stomatal opening, as sugars act as osmolytes, drawing water into the guard cells and increasing their turgor pressure, which in turn causes the stomata to open. 

Stomata are pores on the surface of leaves and other plant organs that allow for gas exchange (CO\(_2\) uptake for photosynthesis, and O\(_2\) release). Each stoma is surrounded by a pair of specialized cells called guard cells. 

The opening and closing of the stomatal pore is controlled by the turgor pressure (water pressure) within the guard cells. When guard cells become turgid (swollen with water), they swell, causing the stomatal pore to open. Conversely, when guard cells become flaccid (lacking water), they shrink, closing the stomatal pore. Sugars, particularly those produced by photosynthesis in mesophyll cells, can act as osmolytes (solutes that affect water potential) in the guard cells. 

• How Sugars Influence Stomatal Opening:

  • When sugar levels increase in the guard cells, the sugar acts as an osmolyte, increasing the osmotic potential (or decreasing the water potential) within the guard cells. 
  • This osmotic gradient causes water to move into the guard cells from surrounding cells, increasing turgor pressure. 
  • The increased turgor pressure causes the guard cells to swell, pushing the stomatal pore open.