Answer:
phototropism
Explanation:
The student was investigating phototropism.
The student wanted to know the response of the roots to light, that is why he exposed them to light.
Roots naturally exhibit two types of tropisms.
The first is gravitropism whereby they tend to grow downwards.
The second is hydrotropism whereby they grow towards the direction of water.
In the above experiment, no water was provided, the roots grew away from the light source but not specifically downwards.
