Answer:
a) Auxin
b) positive response is response which is in direction of stimulus while negative is opposite to that
c) i) negative geotropism
ii) positive chemotropism
iii) negative phototropism
d) i) when the stimulus of light comes to plant , its shoots grow towards light while roots away from light ......shoots have leaves which prepare food while roots do not have to prepare food
ii) similar to above due to the gravity of the earth the roots go down and shoots showing negative geotropism goes up