Answer and Explanation: The figure below shows the doses of BPA administered to the female mice over time.
An experiment is used to determine cause and effect among variables. When the research is for the impact of a treatment, researchers randomly separate individuals in two groups:
- Control Group doesn't receive any treament or a placebo or a treatment whose outcome is already known;
- Treatment Group receives the treatment;
For the female mice on the image below, in the First Group is not injected any dosage of BPA, so they are the control group, while the others are treatment group.
The variables in a experiment are classified as independents or dependents:
- Independent Variable is the cause;
- Dependent Variable is the effect;
For the BPA research, since it is the effect of BPA over time on the mice's cells it is being investigated, dosage of BPA is the independent variable and time is the dependent variable.