Liquefaction
a).is caused by volcanic eruptions
b).happens when tectonic plates collide
c).wears down rocks and creates beautiful arches
d).happens when soil is weakened by water and seismic waves

D).happens when soil is weakened by water and seismic waves              

Explanation:

Liquefaction is a phenomenon in which the strength of the soil weakens due to the earthquake or any other load. The solid behaves like a liquid. Liquefaction of soil below structures cause lot of damage during Earthquakes.The soil looses stiffness due to seismic waves and water.

Thus, the correct option is D.

b.

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