Natural selection is best described as
a. disruptive selection
b. stabilizing selection
c. a mechanism of evolution
d. directional selection
regular distribution is observed for many organisms due to
a. the need to maximize exposure to sunlight
b. the need to avoid predators
c. interactions between individuals
d. the plentiful availability of water

Natural selection is the differences in survival and reproduction as the consequence of differences in phenotypes. According to Darwin's theory of evolution, natural selection is the only factor that affects a frequency of different variations and it is the only mechanism of evolution. 

Q2. The answer is c. interactions between individuals.

Organisms interact with other organisms or abiotic factors in some system. The interaction between individuals affects their regular distribution. For example, if two groups are in competition for resources, to maximize resource utilization, they will probably live in different areas or will defend territory. Also, some symbiotic organisms are expect to be distributed similarly.

the "dirty dozen" chemicals banned in an international treaty are formally known as persistent organic pollutants, or pops. the united nations environment program provided this background on what they are and what they can do to humans and wildlife.

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genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).