'A big tree falls in a forest but its roots are still in contact with the soil. The branches of this fallen tree grow straight up (vertically). This happens in response to(a) water and light (b) water and minerals (c) gravity and water (d) light and gravity'

(d) light and gravity.

The root shows positive geotropism while stem or other aerial parts of plant show negative geotropism. Hence, the plant stem grows towards the light in the upward direction against the force of gravity.