A, D, and not sure but maybe E
A control group in a scientific experiment is a group separated from the rest of the experiment, where the independent variable being tested cannot influence the results. This isolates the independent variable's effects on the experiment and can help rule out alternative explanations of the experimental results.
Answer:
a weightlifter lifts a 20 kilogram barbell above his head
When the liquid metal that creates the outer core of the earth passes through a magnetic field, it begins to carry the electric current through the liquid. This current makes its own, much stronger magnetic field.
