Instrument that can be used to demonstrate transpirational pull due to vaporization of water is

The correct option is C Atmometer
An atmometer or evaporimeter is a scientific instrument used for measuring the rate of water evaporation from a wet surface to the atmosphere. Atmometer is an apparatus consisting of a porous pot connected to a narrow glass tube. The apparatus is filled with air free water. The free end of the glass tube is dipped in beaker containing mercury. As water evaporates from the porous pot, mercury begins to rise upwards in the glass tube showing a pull due to evaporation similar to pull by transpiration.

Thus, the correct answer is option B.