Drosera rotundifolia has tentacle which shows movements called:

Thigmonastic movement is a plant's nastic response to being touched. Another name for thigmonastic movement is seismonastic movement.

Carnivorous plants such as Dionaea and Drosera show this movement in reaction to contact with an insect. Due to thigmonastic movement, the tentacles of these plants migrate inwards to entrap the prey. 

Hence, the correct option is thigmonastic movement.