Passage Summary: A researcher found that moms who get regular medical checkups during pregnancy tend to have heavier, healthier babies. Because of this, the researcher claims the checkups are what cause the babies to be healthier.

Conclusion: Providing adequate prenatal care is a direct cause of reducing the risk of a baby having a low birth weight.

Reasoning: Hospital records show a correlation where mothers who received prenatal care were less likely to have low birth weight babies than those who did not.

Analysis: The researcher is making a classic 'correlation equals causation' error. Just because prenatal care and healthy birth weights happen together doesn't mean one caused the other. To weaken this, look for an answer that suggests a third factor—like the mother's socio-economic status or overall health habits—might be responsible for both the prenatal care and the birth weight. If mothers who are already healthier are more likely to seek care, the care itself might not be the primary reason for the baby's weight. A good 'Weaken' answer will often provide this alternative explanation.