Can someone clearly explain this to me ? Though this IR (CR) question looks simple at the outset, there is fair amount of ambiguity in the answers provided. This is an official GMAT Prep Test question.
Marco: Giant kangaroos - one of several extinct species of large mammals (megafauna) - went extinct around 46,000 years ago. The deposits and wear patterns on the teeth of these animals from around the time of their extinction indicate that they fed mostly on saltbrush shrubs. Saltbrush thrives in arid climates, so it is not likely that the kangaroos' food supply was adversely affected by the increasing aridity of the climate at that time. Thus, something else would have to account for their extinction, and the best candidate for that cause is predation by humans.
Fatima: That argument alone is not likely to satisfy many researchers in this field. Have you found any other evidence to bolster your conclusion ?
Select Marco for the statement that, if true, most justifies Marco's assertions, and select Fatima, for the statement that, if true, most justifies Fatima's skepticism about Marco's assertions. Make only two selections, one in each column.
A) Giant kangaroos became extinct during a period that was less arid than previous periods they endured.
B)Many researchers believe humans first arrived in Australia around 40,000 years ago.
C)Approximately 60 different species in Australia died out in the wave of extinctions around 46,000 years ago.
D)Fossils of giant kangaroos also sho evidence that those animals' diets routinely included plants other than saltbrush.
E)Several types of megafauna larger than the giant kangaroo went extinct around 46,000 years ago.
Ans: Marco's assertions : A
Fatima's skepticism: B
Marco: Giant kangaroos - one of several extinct species of large mammals (megafauna) - went extinct around 46,000 years ago. The deposits and wear patterns on the teeth of these animals from around the time of their extinction indicate that they fed mostly on saltbrush shrubs. Saltbrush thrives in arid climates, so it is not likely that the kangaroos' food supply was adversely affected by the increasing aridity of the climate at that time. Thus, something else would have to account for their extinction, and the best candidate for that cause is predation by humans.
Fatima: That argument alone is not likely to satisfy many researchers in this field. Have you found any other evidence to bolster your conclusion ?
Select Marco for the statement that, if true, most justifies Marco's assertions, and select Fatima, for the statement that, if true, most justifies Fatima's skepticism about Marco's assertions. Make only two selections, one in each column.
A) Giant kangaroos became extinct during a period that was less arid than previous periods they endured.
B)Many researchers believe humans first arrived in Australia around 40,000 years ago.
C)Approximately 60 different species in Australia died out in the wave of extinctions around 46,000 years ago.
D)Fossils of giant kangaroos also sho evidence that those animals' diets routinely included plants other than saltbrush.
E)Several types of megafauna larger than the giant kangaroo went extinct around 46,000 years ago.
Ans: Marco's assertions : A
Fatima's skepticism: B
