Answer:
Auxin increases in concentration on the side of the shoots and the roots that faces away from the light.
Explanation:
Auxin is a growth hormone in plants.it is promotes elongation of roots  and shoots. It is very sensitive to light. when the plant is exposed to light, the auxin in the  exposed part  of  the shoots breaks down. And diffuses to the shady part not exposed to light..
The higher concentration of auxin at this parts, promotes accelerated growth, which  caused the part to bend to of this shoot to grow faster than the other part, and bends towards light.
While the roots grows towards.