The correct answer is A. Ganong’s potometer.
A Ganong’s potometer is a device used to measure the rate of transpiration in plants. It consists of a glass tube with a water reservoir at one end and a funnel at the other. The funnel is placed over a leaf, and the water reservoir is filled with water. The rate of transpiration is then measured by the amount of water that flows out of the reservoir over a given period of time.
B. Auxanometer is a device used to measure the growth of plants. It consists of a metal rod that is attached to the plant. The rod is connected to a scale, and the growth of the plant is measured by the amount of movement of the rod on the scale.
C. Respirometer is a device used to measure the rate of respiration in plants. It consists of a chamber that is filled with air and a gas analyzer. The rate of respiration is then measured by the amount of carbon dioxide that is produced by the plant over a given period of time.
D. Porometer is a device used to measure the stomata conductance of leaves. It consists of a chamber that is filled with water and a pressure gauge. The stomata conductance is then measured by the amount of water that flows through the stomata over a given period of time.