Answer:
option 3 in 1st one and option 4 in 2nd one I think
Answer:
B. Is what the scientists manipulate in the experiment.
Explanation:
The Independent variable is not dependent, or doesn't rely, on another variable in the experiment. So, it would make the most sense that they would manipulate the Independent so that they can watch and see how the dependent variable reacts to the manipulation, or the change, in the independent variable.
Go off kacey, as she should.
Chemistry is just about chemical reactions, properties of matter. Unless it is bio-chemistry which is just the mix of two.