A scientist wants to prove that certain chemicals in cosmetics are likely to cause harm to developing fetuses, when used by a pregnant woman. What is the most likely limitation she will face in her scientific design?

Testing whether chemicals harm developing fetuses could require exposing pregnant people and their fetuses to substances that may be dangerous. Researchers cannot ethically deliberately put human participants at serious risk, so ethical concerns about experimental subjects are the most likely limitation. The correct choice is “limitations due to ethical concerns about experimental subjects.”

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