SAT English Practice Question

A study found that people who regularly consume foods rich in antioxidants, such as berries and leafy green vegetables, tend to have lower rates of heart disease and certain types of cancer than people who do not regularly consume these foods. However, the researchers cautioned that it is not possible to conclude from this study that consuming antioxidant-rich foods causes people to be healthier. What is the most likely reason why the researchers made this caution?

1. A.the study did not measure the amount of antioxidants consumed by each participant.
2. B.the study did not include a control group that did not consume antioxidant-rich foods.
3. C.the study did not establish a causal relationship between antioxidant-rich foods and lower rates of disease.
4. D.the study did not account for other factors, such as genetics, that could also influence rates of heart disease and cancer.