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 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?
(a) the growth of new rings in a tree is not a function of levels of precipitation.
(b) only the brazilian ash loses rings because of excessive heat.
(c) only one day of temperatures above 95 degrees fahrenheit is needed to cause the brazilian ash to lose a ring.
(d) the internal rings of all trees are of uniform thickness.
(e) the number of rings that will be lost when the temperature exceeds 95 degrees fahrenheit is not predictable