<span>Basically, the breeder selects individuals with desired traits (high milk yields, lots of wool etc) and keeps breeding then until the descendants display a very exaggerated set of traits.
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It will become a theory after repeated experimentation
The correct option is A.
Living organisms depend on their environment to survive, when there are changes in the environment which are not favorable to the living organisms, it will eventually leads to the wiping out of the living organisms. As time goes on and the environment recover, the living organisms that will be found in the new environment are those who will be able to survive in it.
It is the independent variable. Because it can have an effect on the dependent variable.