Explanation
Correct answer: C.
Choice C is the best answer because it presents a detail that, if true, would most directly support the researcher’s claim about the difficulty of determining olive tree age by ring counting. The text explains that for many trees, counting the dark rings visible in a tree stump is a reliable method for determining the tree’s age. However, if olive trees have growth rings that are difficult to see, it would be hard to count the individual rings. Therefore, the ring-counting method would be challenging or impossible to use for olive trees. This directly supports the researcher’s claim that the ring-counting method often can’t be used for olive trees because it identifies a specific characteristic of olive trees that could render this approach impracticable.
Why the other choices are wrong
Choice A
Choice A is incorrect because the probable age of the oldest olive tree doesn’t explain why counting rings wouldn’t work for determining olive tree age. The older age of some olive trees might make counting more tedious but doesn’t pose an insurmountable obstacle to adopting the method. The researcher’s claim is about the feasibility of the ring-counting method for olive trees, not about the potential impracticality of employing this method for particularly long-lived trees.
Choice B
Choice B is incorrect because the fact that narrow growth rings might indicate harsh growing conditions has no direct bearing on the claim that counting rings often can’t be used to determine olive tree age. It is possible that growth rings that are too narrowly spaced might be difficult to count, but the researcher’s claim relates to the inapplicability of the ring-counting method to olive trees in general rather than to olive trees that have experienced harsh conditions. Moreover, as long as they are visible, even narrow growth rings might permit the ring-counting method to be used to determine tree age.
Choice D
Choice D is incorrect because the ideal climate conditions for olive trees don’t explain why counting rings wouldn’t work as a method for determining their age. While growing conditions might affect ring formation patterns, the simple fact that olive trees thrive in hot, dry environments doesn’t directly address why the conventional method of counting rings would be ineffective for determining their age.