The elasticity of a substance describes how fast or slow its particles bounce back and forth as move through the object a: vibrations b: chemicals c: electrons d: surface waves

The answer is D. Surface Waves.  The wave pass through the medium for example a guitar string when you strum the guitar as a result of the particles bumping back and forth on each other and the interactions of both particles in the medium cause the sound wave to travel through the medium.

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:

b brown mice / white sand dunes