1. - control.
2. - quantitive data
3. - qualitative data
4. - observation
Answer:
D
Explanation:
Fossils tell us where they came from.
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Answer:
Between one-third and one-half of all fertilized eggs never fully implant. A pregnancy is considered to be established only after implantation is complete
Answer:
Free radicals are unstable atoms that can damage cells, causing illness and aging. Free radicals are linked to aging and a host of diseases, but little is known about their role in human health, or how to prevent them from making people sick.
Explanation: