A recent study observed that countries with higher per capita chocolate consumption tend to win more Nobel Prizes. Researchers concluded that chocolate consumption enhances cognitive function, leading to greater scientific achievement. Which of the following, if true, would most weaken the researchers' conclusion?
✓ Correct Answer: Option B
This option introduces a strong confounding variable (wealth/research funding) that could explain the correlation, undermining the proposed direct causal link between chocolate and cognitive function.