Answer: D
Experiment 1 has a confounding variable related to the mass of the rockets. Any variation in mass may cause a discrepancy in the distance traveled.
This is the answer to the question because:
- Both experiments do have a confounding variable.
- Experiment 1 doesn't have to stay constant.
- A double-blind experiment will not do anything to the placebo.
- High blood pressure people will not make the results confusing.
The answer has to be the option D. Hope this helps you!
1. Cenozoic ERA
2. Mesozoic ERA
3. Paleozoic ERA
