Generally, epidemiological studies ________.
A. involve in-vitro experimentation
B. prove positive correlations
C. establish causation without observations
D. cannot determine cause-and-effect relationships
Answer: D
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Which of the following is true of the placenta?
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Name the protein in wheat, barley and rye which causes abnormal reactions in some persons
What will be an ideal response?
Which of the following is a characteristic of neural tube defects?
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