Q11 - In the past, infants who were not breast-fed

[Laura Damone]

Question Type:
Most Strongly Supported - Inference

Stimulus Breakdown:
Inference questions tend not to have arguments, and this is no exception. So, we just need the facts: Babies that weren't breast-fed used to be given cow's milk. Doctors advised boiling cow milk to prevent potentially fatal infections. Once this advice was widely implemented, that was an alarming increase in the incidence of scurvy in infants. Breast fed infants didn't get scurvy. Scurvy is caused by vitamin C deficiency.

Answer Anticipation:
We have a change in practice (boiling the milk) correlated with a change in outcome (scurvy). We also have a control group (the breast fed infants), for whom there was no change in practice and no change in outcome. Together, these things support a causal relationship between the change in practice and the change in outcome. Something about the boiling of milk led to the vitamin C deficiency.

Correct answer:
A

Answer choice analysis:
(A) This seems well supported! If the infants drinking the boiled cow milk are getting scurvy and the breast-fed infants aren't, it makes sense that the boiled cow milk makes less vitamin C available. Does this absolutely HAVE to be true? No. Maybe the boiled milk contributes to vitamin C deficiency in other ways, like blocking absorption of the vitamin. This is a definite contender, but I'm not ready to select it until I've ruled out the other four choices.

(B) No way. The frequency of gastro infections in drinkers of non-boiled cows milk isn't inferable from the facts.

(C) The existence and causes of gastro infections among the breastfed isn't inferable, either.

(D) Nope. We can't infer anything about what docs new and what they didn't.

(E) Another no. We don't know what percentage of mothers breast-fed.

Takeaway/Pattern:
Remember that in Most Strongly Supported Inference questions, the answer doesn't need to be 100% provable. If you have doubts, defer, then come back to that answer after working wrong to right. If it's the only answer left, you have a winner. If there are multiple contenders, weigh them against each other and the stimulus to determine which is better supported.