H D4 TS Q23 – Selective High School

Dr Marcelle: “At 10 years old, the children with parents who smoke, are shorter (on average) than the children of non-smoking parents. Therefore, parents who smoke tend to reduce the growth rate of their children.”

Which one of the following shows the mistake Dr Marcelle has made?

By 18 years old the children of smokers may be the same size as the other children. Lower average heights in 10-year-old children may be associated with parental smoking, but not caused by it. Countries that have the highest number of smokers don’t track the heights of their population. The children of smokers might be more advanced in other ways than the children of non-smokers.

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Which one of the following shows the mistake Dr Marcelle has made?