Question

which of the following mechanism is best suitable for opening and closing of stomata

Answer 1

It's point A because guard cells is after the stomata pour

Answer 2

As mentioned above.. so many things are there which affect opening and closing of stomatal
But it all depends upon the guard cells...
As from near by mesophyll cells the water comes and accumulation of water by guard cells...
Then the size increases opening the stomach..

As the stomata opens solute gets reduced..
This makes the water from guard cells to move away.. and closing occurs

For this option (1) is more appropriate