In this task, you are given a paragraph, and your task is to construct a question from the given passage. Construct question in such a way that (i) it is well explained in the paragraph, (ii) the words may/may not be present in the paragraph, (iii) it should start with what/how/describe. Avoid creating a question that (i) is just relevant to one or two sentences, and (ii) not relevant to passage.

Techtonic plates in the earths crust move. Movement creates fissures. Upheavals in the crust. Fissures allow lava to erupt into volcanoes at the surface. Volcanoes erupt, accumulating lava, forming mountains. Upheavals in the crust become their own mountains.
How do mountains form?

Magma rises to the surface during a volcano. The magma undergoes changes in temperature. The magma undergoes changes in pressure. The magma cools. The magma solidifies. The magma crystallizes. Igneous rock is formed.
How does igneous rock form?

The cornea and lens refract light into a small image. Shine it on the retina. The retina's rods and cones convert it to electrical pulses. The optic nerve carries electrical pulses through the optic canal. Nerve fibers end in the lateral geniculate nucleus and the visual cortex.
How does the human vision system work?