#22 - Researchers have found that children in large families

[ashpine17]

Maybe the overall incidence of allergies fell in these countries due to reduction of air pollution but the incidence of allergies among younger siblings across family sizes (whether they be large or small) are the same.

One lingering question I have is that many explanations put an emphasis on younger siblings; why pay attention to that specifically?

[Rachael Wilkenfeld]

Hi ashpine,

You are spot on in regards to answer choice (A). We don't know for that answer choice how the pattern holds. Are younger children still seeing lower allergy rates? Even if the average family size is down, is that because there are fewer families with any children and some families with very many children? How many younger siblings are there, and what is their allergy situation? We just don't know enough from answer choice (A) to have an impact on the argument.

The key to this one isn't the younger children--it's the germ exposure. Germ exposure is the reason that they think that these children have fewer allergies. So answer choice (E) that gives kids more exposure, and fewer allergies would support the causal relationship given in the stimulus.

Hope that helps