For what subjects? I guess I can try :)
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3 there are 3 of them....
Answer:
The two main variables in an experiment are the independent and dependent variable. An independent variable is the variable that is changed or controlled in a scientific experiment to test the effects on the dependent variable. A dependent variable is the variable being tested and measured in a scientific experiment.
Darwin discovered that the same species of organisms had different traits from one island to the next. According to Darwin, this happened because the organism had. A) adapted to better survive in their habitat.