Manipulative experiments alter levels of a predictor variable (or factor), and then measures how one or more variables respond to these alterations. ... Natural experiments-An observational study in which we take advantage of natural variation that is present in the variable of interest.
Answer:
b
Explanation:
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The four steps to comprehend health concepts related to health promotion and disease prevention are: (1) study health information; (2) ask questions about information you don't understand; (3) use health knowledge to from health concepts; (4) and use health concepts to reduce your risk.
There are five levels of cell organization recognized by biologists.
