Answer:I found heart disease and cancer online by CDC in 2017
Explanation:
1. True- because scientific theory means that <span>idea supported through research that attempts to explain existing observations or predict new ones.</span>2. False- because a cross-sectional means that its a study that is about different groups.
3. B-<span>An extraneous variable clarifies the relationship between the independent and dependent variables.</span>
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Answer:
I think it might ve the mass