The ability of the Venus Fly-trap to capture insects is due to :

Explanation

(d) : Thigmonastic movements are exhibited by some insectivorous plants such as Dionaea, venus fly trap, Drosera etc. These plants have tentacles, which are sensitive to the stimulus of touch. In the case of the venus flytrap turgor pressure changes occur in which hydrogen ions are rapidly pumped into the walls of cells on the outside of each leaf in response to the action potentials from the trigger hairs. The protons apparently loosen the cell walls so rapidly that the tissue actually becomes flaccid so that cells quickly absorb water, causing the outside of each leaf to expand and the trap to snap shut.