LSAT Question Stem

The statements above, if true, most strongly support which one of the following? 

Logical Reasoning Question Type

This is a Most Strongly supported question. 

Correct Answer

The correct answer to this question is E. 

LSAT Question Complete Explanation

First, let's analyze the passage. It tells us that most land-dwelling vertebrates have rotating limbs with digits, which are useful for land movement. Biologists used to think that this characteristic evolved only after animals left aquatic environments. However, the discovery of Acanthostega, an ancestor of all land vertebrates, challenges this belief. Acanthostega had rotating limbs with digits, but its skeleton was too weak for land movement, and it had internal gills, indicating it was exclusively aquatic.

To simplify this, imagine a group of animals that can climb trees due to a specific feature. Scientists thought this feature evolved after the animals started living in forests. But then they discover an ancient animal with the same feature that lived only in water, not in forests. This challenges their previous belief.

Now, let's examine the question type, which is a Must Be True (MSS) question. We need to find the answer choice that is most strongly supported by the information in the passage.

a) The passage doesn't provide enough information to conclude that many anatomical characteristics common to most land animals are disadvantageous for underwater survival. We only know about rotating limbs with digits in Acanthostega.

b) We don't have enough information about the anatomical characteristics of most aquatic animals to determine if none of them would be advantageous for land survival.

c) This answer contradicts the passage, which states that Acanthostega was exclusively aquatic and had internal gills. It doesn't suggest that Acanthostega evolved gills after moving to an underwater environment.

d) The passage doesn't provide enough information to conclude that all anatomical characteristics not useful for land movement but common to most land animals represent an advantage for underwater survival.

e) This is the correct answer. The passage tells us that Acanthostega, an aquatic animal, had rotating limbs with digits, a characteristic useful for land movement. This implies that certain anatomical characteristics (rotating limbs with digits) common to some aquatic animals (Acanthostega) represent an advantage for survival on land (useful for land movement).

In summary, the passage challenges the belief that rotating limbs with digits evolved only after animals left aquatic environments by presenting the example of Acanthostega. The correct answer, choice E, is supported by the passage, as it states that certain anatomical characteristics of some aquatic animals can represent an advantage for land survival.