A recent study found that individuals who regularly consume whole grains have a significantly lower risk of heart disease. The researchers concluded that consuming whole grains directly protects against heart disease.
- AThe study only observed participants for five years, which may not be long enough to see the full effects of diet on heart disease.
- BThe amount of whole grains consumed varied significantly among the participants.
- CSome people with a genetic predisposition to heart disease may avoid whole grains due to digestive issues.
- DIndividuals who consume whole grains are also more likely to engage in other healthy behaviors, such as regular exercise and avoiding processed foods.
Show answer & explanationAnswer & explanation
Correct answer: D. Individuals who consume whole grains are also more likely to engage in other healthy behaviors, such as regular exercise and avoiding processed foods.
The argument concludes that whole grains directly protect against heart disease. Option A introduces a confounding variable: a generally healthy lifestyle. If people who eat whole grains also exercise and avoid processed foods, then these other healthy behaviors, rather than whole grains alone, could be responsible for the lower risk of heart disease.
Why the other options are wrong
- A. This suggests a limitation of the study's duration but doesn't offer an alternative cause for the observed correlation within the study period.
- B. Variability in consumption might affect the *strength* of the correlation, but it doesn't provide an alternative cause for the observed correlation.
- C. This suggests a reverse causation for a specific subgroup, but doesn't weaken the general claim that whole grains protect against heart disease for the general population.
Confounding Variable (Causal Flaw)
A flaw in reasoning where an argument mistakenly attributes a causal relationship due to the presence of an unacknowledged third variable that influences both the presumed cause and effect.
- Creates an illusion of direct causation.
- The confounding variable is correlated with both the independent and dependent variables.
- Must be controlled for in studies to establish true causation.
Memory trick: Don't just link the chain, check for a hidden main!