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Summarize Argument
The advertisement claims that at least 50 million North Americans should take lactase supplements to help them digest dairy. How do we know? Well, in one study where participants drank a liter of milk on an empty stomach, a significant proportion had digestion troubles. By applying that proportion to the North American population, we get to 50 million.
Notable Assumptions
The advertisement assumes that drinking a liter of milk on an empty stomach accurately reflects people’s everyday dairy digestion needs. If people can generally handle smaller amounts of dairy just fine, then the study could be misleading.
The author also assumes that the sample group is equivalent to the general North American population—meaning that the participants weren’t unusually likely to be lactose intolerant.
The author also assumes that the sample group is equivalent to the general North American population—meaning that the participants weren’t unusually likely to be lactose intolerant.
A
Eating solid food when drinking milk can decrease the amount of lactase produced by the body.
This does not weaken the argument, We don’t know whether people normally drink milk while by itself or while eating food. If the former, then that makes no difference, because the participants weren’t eating. If the latter, then maybe even more people need lactase!
B
Most people who consume dairy products consume less lactose at each meal than the amount found in a liter of milk.
This weakens the argument by casting doubt on whether the study cited represents people’s normal dairy digestive needs. Maybe most people produce enough lactase for their usual dietary habits, even if a whole liter of milk at once would cause some problems.
C
The production of lactase by the human body increases with age.
This does not weaken the argument because we don’t know anything about the age of the study participants, nor how that corresponds to the general population. If the participants were younger than average, that might be a problem, but we have no idea.
D
Lactose intolerance can interfere with proper nutrition.
This does not weaken the argument, because it doesn’t tell us anything about how representative the study was of the general population. Sure, lactose intolerant people should take lactase—but we still don’t know if that means 50 million people.
E
Some dairy foods, such as cheese, contain a form of lactose more difficult to digest than that found in milk.
This does not weaken the argument, firstly because we don’t know what kind of dairy people usually consume, and secondly because if anything it indicates a greater need for lactase than the study does. Either way, this doesn’t undermine the “at least 50 million people” claim.
"Surprising" Phenomenon
Some patients wear glasses or contacts after receiving RK surgery, which is meant to make them unnecessary.
Objective
The correct answer must fail to explain why some RK patients need glasses or contacts after receiving surgery. Every wrong answer, meanwhile, will state a difference between the intentions of RK surgery and its actual effect on some patients that results in those patients wearing glasses or contacts afterward.
A
As the eye heals from an operation to correct nearsightedness, it may in fact overcorrect, causing the person to be farsighted.
This would make glasses or contacts necessary for some RK patients. An overcorrecting eye would necessitate glasses or contacts to correct the new problem caused by the surgery.
B
The more severe a patient’s nearsightedness, the less effective the corneal reshaping of RK will be in correcting the problem.
This implies that very nearsighted patients may not have their vision completely corrected by RK surgery, which would make eyeglasses or contacts necessary afterward.
C
Occasionally an RK patient’s eyes may heal differently, causing a difference in the two eyes’ visual acuity that can be overcome only with corrective lenses.
This would explain why some RK patients require glasses or contacts. If their eyes heal differently, the surgery will cause a new problem that glasses or contacts can fix.
D
RK patients who originally suffered from only mild nearsightedness may, if the cornea does not heal evenly, develop an astigmatism that requires corrective lenses.
This would explain why some RK patients require glasses or contacts. If they develop an astigmatism, glasses or contacts may be necessary to correct a new problem caused by the surgery.
E
Those who choose to undergo RK tend to be as nearsighted before this operation as those who choose not to undergo RK.
This does not explain why RK patients would need glasses or contacts after surgery. It refers only to patients before they receive the surgery, not the consequences of the surgery.