The argument tells us that younger siblings in larger families are less likely to develop allergies due to exposure to germs during infancy. The correct answer choice provides additional evidence supporting the relationship between exposure to germs during infancy and lower likelihood of allergies. (E) tells us that children from small families that entered day care before age one were less likely to develop allergies than children from small families who entered daycare later. The answer choice tells us that neither group of children had exposure to germs at their homes (small families), but one group who entered day care before age one, got exposed to germs in infancy (babies before age one count as infants) were less likely to develop allergies than kids who entered daycare later (not as infants). Since the only difference between these two groups of children is the age when they entered daycare and became exposed to germs, this evidence supports the hypothesis in the stimulus that exposure to germs as an infant correlates with one's likelihood of developing allergies.
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