Most people can gain vitamin C from fruits such as oranges and cantaloupes.  People with Laestrygonian Disease have weakened digestive systems that cannot digest fruit or vitamin supplements.  The easiest foods for these people to digest are grains such as rice and barley.  Regular intake of vitamin C would be extremely beneficial to those who suffer from Laestrygonian Disease, so scientists have figured out a way to create “fortified rice” by infusing rice with high doses of vitamin C.  This fortified rice will provide great benefit to those with Laestrygonian Disease..
Which one of the following is an assumption on which the conclusion depends?
  1. Only people whose diets consist largely of grains would be able to derive benefit from the vitamin C in the fortified rice.
  2. Eventually, this fortified rice will be the optimal way for most people to have a regular intake of vitamin C.
  3. People with Laestrygonian Disease will not be unable to assimilate the form of vitamin C that is present in the fortified rice.
  4. The problems that folks with Laestrygonian Disease have digesting fruit are different from their problems digesting vitamin supplements.
  5. Vitamin C is the only nutrient which can be infused into rice in such high quantities without compromising the nutritional integrity of the vitamin.


The correct option is C People with Laestrygonian Disease will not be unable to assimilate the form of vitamin C that is present in the fortified rice.

The credited answer is (C). If folks with Laestrygonian Disease cannot assimilate the Vitamin C in the rice, then it won’t help them, and eating the fortified rice will not provide them any particular benefit. If we negate this option, it shatters the argument. This is a true assumption.
(A) This may be true, although I am skeptical that any human-made improved food would be better than the fruits designed by Nature! Regardless, whether this is true or not does not have any bearing on how helpful the fortified rice will be for the folks with Laestrygonian Disease. This option is incorrect.
(B) This is intriguing. Let’s negate this. Suppose it were the exact same problem, say, the exact same missing enzyme, that made it impossible to digest both fruit and vitamin supplements. Then what? Would that mean they also couldn’t digest the fortified rice, or get the vitamin C they need from it? We cannot say. It’s conceivable that the argument could still work, so negating this does not destroy the argument. This is not an assumption.
(D) Let’s negate this. Suppose the fortified rice benefits everyone—even the no-carbs fanatic who hasn’t touched carbs in a decade: even when this person breaks his carb-fast and has the fortified rice, he has benefit from it. What then? Whether these other people benefit or not from the fortified rice has no bearing on whether it helps the folks with Laestrygonian Disease. This choice is incorrect.
(E) Let’s negate this. Suppose we can infused dozens of other vitamins and minerals into the rice, all with high nutritional yield. That would only be good for the folks with Laestrygonian Disease—the more vitamins, the better! It certainly would not impact whether these folks derived any benefit from the vitamin C in the rice. This choice is incorrect.

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