DNA microarrays allow the rapid and simultaneously SCREENING of many thousands of genes.
They begin to form about 3.8 billion years ago
The answer is difference in density. We know that the high central density suggests the earth must be rich in nickel and iron and that much of the core must be liquid. This lower-density air then rises and is replaced by cooler, higher-density air. The result is atmospheric circulation that drives the weather and climate through redistribution of thermal energy.
I think its B. Im not sure
