Juvenile Plants Found Growing on Bare Ground and in Patches of Vegetation for Five Species Species

Choice D is the best answer because it provides the most direct support from the table for the claim that the animals growing in close proximity to other animals gained an advantage at an early developmental stage. The table shows the total number of juvenile animals from five species that were found growing on bare ground and in patches of vegetation as well as the percentage of the total number of each species that were growing in patches of vegetation. For each of the five species, more than 50% of the juvenile animals were growing in patches of vegetation. The text notes, however, that a random distribution of animals across the landscape should result in only about 15% of the animals being found in patches of vegetation. In other words, for each of the five species, the percentage of juvenile animals found growing in patches of vegetation was substantially higher than could be explained by chance alone. This finding supports the claim in the text: if animals growing in patches are overrepresented among animals that have survived to the juvenile stage, as the data show they are, then it suggests that it’s advantageous for animals at an early stage of development to grow in patches of vegetation.  

Choice A is incorrect because the statement that less than 75% of juvenile animals were found growing in patches of vegetation, while true, doesn’t clearly support the claim that the animals growing in close proximity to other animals gained an advantage at an early developmental stage. Saying that less than 75% of animals were found in patches doesn’t indie how the percentage growing in patches compares with the percentage that would be expected to grow in patches on the basis of chance alone, which is the information necessary to evaluate whether the claim in the text has support in the table. Put another way, if the percentage of animals found growing in patches was 15% or less, it would be true that less than 75% were found in patches, but the data would in fact weaken the claim in the text, not strengthen it, since the data would show that growing in patches wasn’t advantageous. Choice B is incorrect because only 12 animals of this species were found growing in patches, which was the lowest number of any species, not the greatest number. Additionally, even if it were true that this species had the greatest number of animals growing in patches, the finding would be irrelevant to the claim that animals of all five species gained an advantage by growing in close proximity to other animals. Choice C is incorrect because 59.1% of the animals of these species were found growing in patches, which is a far greater percentage, not a lower percentage, than what would be expected if animals were randomly distributed (around 15%). Additionally, if it were true that the percentage of animals growing in patches was lower for these species than what would be expected from chance alone, that finding would weaken, not strengthen, the claim that growing in patches is advantageous.