Question

What does a control group show in an experimental investigation?

the effects that the scientists are causing by manipulating variables
how nature would act without manipulation by the researchers
why each part of a system is related to every other part
all parts of a system that scientists are controlling and changin

Answer 1

I believe the answer is A.
A control group is a group that does not change. in order for the scientists and researchers to see what the changes were in the experiment, they look at the controlled group, or the original form in a sense. With my understanding, that’s exactly what the first one is saying. While scientists manipulate variables they refer to the controlled group in order to see the effects of the experiment.
hope this helps!