Bunuel wrote:
Measurements of the extent of amino-acid decomposition in fragments of eggshell found at archaeological sites in such places as southern Africa can be used to obtain accurate dates for sites up to 200,000 years old. Because the decomposition is slower in cool climates, the technique can be used to obtain accurate dates for sites almost a million years old in cooler regions.
The information above provides the most support for which one of the following conclusions?
(A) The oldest archaeological sites are not in southern Africa, but rather in cooler regions of the world.
(B) The amino-acid decomposition that enables eggshells to be used in dating does not take place in other organic matter found at ancient archaeological sites.
(C) If the site being dated had been subject to large unsuspected climatic fluctuations during the time the eggshell has been at the site, application of the technique is less likely to yield accurate results.
(D) After 200,000 years in a cool climate, less than one-fifth of the amino acids in a fragment of eggshell that would provide material for dating with the technique will have decomposed and will thus no longer be suitable for examination by the technique.
(E) Fragments of eggshell are more likely to be found at ancient archaeological sites in warm regions of the world than at such sites in cooler regions.
OFFICIAL EXPLANATION
This is another straightforward, fact-based question. Since the accuracy of the technique depends on temperature, any prolonged change in climate will affect its accuracy. For example, if a particular site now has a cool climate but for most of its past had a tropical climate, then the results from applying the technique would be misleading.
The answer is (C).The other choices are easily dismissed. Choice (A) is not supported by the passage. Climate affects the accuracy of the dating technique, not the age of the site itself. Choice (B) is perhaps second best. Although it is reasonable to assume that some characteristic of eggshells makes them preferable to other organic materials, nothing in the passage implies that the type of amino-acid decomposition found in eggshells is unique. Choice (D) is not supported by the passage. Nothing in the passage indicates the amount of amino acid needed in the eggshell for the technique to be accurate. Finally, choice (E) is not supported by the passage. The passage discusses only the accuracy of the amino-acid method of dating; it does not discuss or imply that fragments of eggshell are more likely to be found in some areas than in others.
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