Aseedling germinating under a stone grows at an angle away from the stone and upward. this response to touch is called
gravitropism
thigmonasty
thigmotropism
skototropism

thigmotropism

Explanation:

Tigmotropism is the curved growth of the plant, which occurs through mechanical stimulation. In the case of the question, the stone stimulated the plant's angular growth.

When the vegetable comes into contact with any consistent object, it grows around it. A very common example of tigmotropism is that of tendrils, which grow wrapped around its support. The winding occurs by a reaction that results from a stimulus from the underside of the tendril, this reaction slows the growth of this side, while the upper side grows faster.

all these collisions do one thing, and that thing is explained in the last option. when dusst, rocks and ice collide, they harden and form giant layers of rocks or hard ice.

d)   to harden materials to form different parts of earth’s layers

hope it ,

bioteacher101