A cup of raw milk, after being heated in a microwave oven to

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A cup of raw milk, after being heated in a microwave oven to 50 degrees Celsius, contains half its initial concentration of a particular enzyme, lysozyme. If, however, the milk reaches that temperature through exposure to a conventional heat source of 50 degrees Celsius, it will contain nearly all of its initial concentration of the enzyme. Therefore, what destroys the enzyme is not heat but microwaves, which generate heat.

Which one of the following, if true, most seriously weakens the argument?

(A) Heating raw milk in a microwave oven to a temperature of 100 degrees Celsius destroys nearly all of the lysozyme initially present in that milk.
(B) Enzymes in raw milk that are destroyed through excessive heating can be replaced by adding enzymes that have been extracted from other sources.
(C) A liquid exposed to a conventional heat source of exactly 50 degrees Celsius will reach that temperature more slowly than it would if it were exposed to a conventional heat source hotter than 50 degrees Celsius.
(D) Milk that has been heated in a microwave oven does not taste noticeably different from milk that has been briefly heated by exposure to a conventional heat source.
(E) Heating any liquid by microwave creates small zones within it that are much hotter than the overall temperature that the liquid will ultimately reach.

OA: E

What's the best approach to determine the answer? Can any experts assist?
Source: — Critical Reasoning |

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by elias.latour.apex » Tue Dec 26, 2017 6:52 am
Our first goal is to determine the conclusion of the argument. It is found after the word therefore.

The argument basically says that the enzyme is destroyed by the microwaves emitted by microwave ovens. Since our goal is to weaken the argument, we must find an alternate cause -- something other than the microwaves that destroy the enzyme. Only answer choice (E) does so. It suggests that pockets of extreme heat may occur, damaging the enzyme more than a standard 50 degree C temperature would.
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