Which causes natural selection to occur?
a-populations below the carrying capacity
b-a lack of competition
c-the presence of predators
d-unlimited resources

silty loam

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in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation:

if you know your abc's you should be able to get your answer or just use google