Answer:
I would say fossil evidence because fossil and rock clues are what led to Wegener's theory of Continental Drift
There's tropism and stimulus, for starters. Gravity, light, and touch can all be used as stimuli. So it is debatable... If the plant is reaching upwards towards a window that is above it... It would then be light, and the plant's response would be to reach upward.
Hope this helps and if it does, don't be afraid to give my answer a "Thanks" and maybe a Brainliest?
The answer is Sensory Neurons