The popular notion that a tree's age can be determined by counting the number of internal rings in its trunk
is generally true.
However, to help regulate the internal temperature of the tree, the outermost layers of wood of the Brazilian ash often peel away when the temperature exceeds 95 degrees Fahrenheit, leaving the tree with fewer rings than it would otherwise have. So if the temperature in the Brazilian ash's environment never exceeded 95 degrees Fahrenheit, its rings would be a reliable measure of the tree's age.
Which of the following is an assumption on which the argument above depends?
(B) Only the Brazilian ash loses rings because of excessive heat...................we are bothered about this particular tree. It does not matter if others lose rings due to some reason.
(C) Only one day of temperatures above 95 degrees Fahrenheit is needed to cause the Brazilian ash to lose a ring........duration of heat exposure need not be assumed.
(D) The internal rings of all trees are of uniform thickness.....................thickness is additional information and need not be assumed.
While we can easily eliminate options B, C and D since they are out of scope.
Most of the candidates above(including me) got stuck between A and E.
(A) The growth of new rings in a tree is not a function of levels of precipitation..............TRAP choice. This seems to indicate that during the scenario of more than 95 degrees Fahrenheit temperature tree only loses rings and does not grow them. This seems to divert us towards reverse causality assumption but there is no reason to assume anything like that regarding growth of new rings.
(E) The number of rings that will be lost when the temperature exceeds 95 degrees Fahrenheit is not predictableThis may not look as attractive as option A but is the correct answer and can be veified through negation test.
If the number of rings is predictable then we can easily decide the tree age even if in high temperatures and this collapses the argument.
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