Which of the following is the best explanation why is the Earth's inner core solid? Question 2 options:

The particles are no longer moving as fast because it has cooled to a solid.

Because the inner core is the same temperature as the sun.

Because it's made of a mixture of iron and nickel which are only found in a solid state.

The pressure from the other layers of the Earth cause the inner core to be solid.

The pressure of all the other layers makes it solid

Explanation:

The weight is so great, it is solid

1) gene flow

- it is described as the transfer of genes from one population to another population so that frequency of gene is increased.

-a zebra migrates to join a different herd of zebras.

2) natural selection

- a mechanism of evolutionary change in which individuals with advantageous traits survive and reproduce whereas the others ( those that can not adapt) eliminate from the population.

-competition for sunlight leads to taller trees.

3) mutation

- permanent change in the nucleotide sequence of dna ( genetic material) that could have harmful or useful consequences.

-the dna of a snake changes to make its venom stronger.

4) genetic drift - it is a random phenomenon ( that occurs by chance such as fire) that results in change in the gene frequency in a small population.    

-a grassfire randomly sweeps through a population of buffalo and kills most of the animals.

explanation: