Answer:
D. We can control some of the factors, but not all of them.
Answer:
No; the study is based on a volunteer sample, which may be very different from a randomly selected one.
Explanation
Her plan cannot be effective because she could base her own judgenent on samples that was randomly selected for consideration.
Answer:
the answer is that the tobacco is very bad
Explanation:
Are there multiple choice options?
Answer:
EndNote. This is a multifunctional tool to help you better organise your research, and it is recommended by universities such as Texas A&M University. ...
Todoist. Do you often get distracted while researching online? ...
RefWorks. ...
DeepDyve. ...
Internet Public Library. ...
Project Gutenberg. ...
Conclusion.
Explanation: