A tissue through which gases are exchanged between the blood and the air in the lungs. a) stratified squamous epithelium
b) simple squamous epithelium
c) simple culumnar epithelium
d) simple cuboidal epithelium

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

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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

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bioteacher101