Now, say you tell a friend what happened with the smooth bricks. She says that because of the way the smooth bricks have interfered with your building process, she can determine what order the chain of bricks was supposed to be in, without even looking at them. However, she does ask you to label each of the smooth bricks with an LED light matching the color of the brick, so that the only bricks she can identify are the ends of each segment. These LED lights labeling the smooth bricks represent

select answer
pigment tracers
phosphate groups
nucleotides

answer: land bridge theory. land bridge theory held that shifting portions of dry land explained the finding of identical species on different continents. plate tectonic theory eventually eliminated the land bridge theory.

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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