Answer: C) a factor that may affect an experiment or investigation
Explanation:
This is the best answer. A and B can be eliminated. D describes a controlled variable which is more specific than a scientific variable, thus C is the best answer. It is the best description of just a scientific variable.
You will your on this certain day hope this helped
Oxygen gas contributes to the green house effect
I think all of the above...
because I know they built aqueducts and sewers, so since 2 of they are correct, then all 3 must be.