The correct option is B If the assertion is true but the reason is false
Nastic movements are non-directional movements in which the response is determined by the structure of the responsive organ and not the direction of the stimulus. Touch responses in Mimosa are an example of movements that do not necessarily occur towards or away from the stimulus. The movement is produced due to turgot changes in the cells of pulvinus or swollen area lying at the base of the petiole, pinnae and pinnules.
So, the correct answer is C 'If the assertion is true but the reason is false'