Answer: A. nastic response
Explanation:
The thigmonasty is a kind of response shown by a plant towards touch and vibration stimuli. It is generally produce in response to changes in plants that occur due to turgor pressure within a cell. The plants generally show this kind of response so as to decrease their surface area so that they can be protected by the grazing herbivores. Also some insectivorous plants like Venus fly trap use it to trap insects when they come in contact of the plant.
On the basis of the above explanation, The leaves of a plant fold inward when touched as a way to defend themselves from potential harm is the example of A. nastic response.
