Stomatal opening and closing is due to the permeability of the guard cell. This fact was revealed by

Comment on the experimental setup. Will the mercury level fluctuate (go up/down) if phenyl mercuric acetate is sprayed on leaves?

The shoot pressure is measured by

Transpiration is measured by

Match the theories given in column-$I$ with the names of scientists listed in column-$II$. Choose the answer which gives the correct combination of the alphabets.

Column-$I$ (Names of theories)	Column-$II$ (Names of scientists)
$(A)$ Relay pump theory	$(p)$ Stocking
$(B)$ Transpiration cohesion theory	$(q)$ Sir $J$.$C$. Bose
$(C)$ Mass flow	$(r)$ Godlewski
$(D)$ Pulsation theory	$(s)$ Dixon and Joly
	$(t)$ Ernst Munch

Potometer and clinostat are used to study