LSAT Explanation PT 44, S2, Q15: According to current geological theory, the

LSAT Question Stem

Which one of the following, if true, most strengthens the argument above? 

Logical Reasoning Question Type

This is a Strengthen question. 

Correct Answer

The correct answer to this question is D. 

LSAT Question Complete Explanation

Let's first analyze the argument in the passage. The argument's structure is as follows:

1. Premise: Melting ice at the end of the Ice Age reduced the weight on parts of the earth's crust.

2. Premise: This reduction in weight caused lasting cracks in the earth's crust in some parts.

3. Premise: At the end of the Ice Age, Sweden experienced severe earthquakes.

4. Conclusion: It is likely that the melting of the ice contributed to these earthquakes in Sweden.

To help understand this argument, let's use a simple example. Imagine a heavy book pressing down on a piece of clay. When you remove the book, the clay cracks due to the sudden change in pressure. Now, if we notice that the table where the clay was placed shook when the book was removed, we might conclude that the cracking of the clay contributed to the shaking of the table.

An "Evaluate" question for this argument would be: "Is there a connection between the cracking of the earth's crust and the occurrence of earthquakes?"

Now let's examine the answer choices for the question, which asks us to strengthen the argument:

a) The earth's crust tends to crack whenever there is a sudden change in the pressures affecting it.

- This answer choice explains why the earth's crust cracked, but it doesn't establish a connection between the cracks and the earthquakes. So, it doesn't strengthen the argument.

b) There are various areas in Northern Europe that show cracks in the earth's crust.

- This answer choice provides evidence that the earth's crust cracked in other areas, but it doesn't show a connection between the cracks and earthquakes. Therefore, it doesn't strengthen the argument.

c) Evidence of severe earthquakes around the time of the end of the Ice Age can be found in parts of northern Canada.

- This answer choice provides information about earthquakes in another region, but it doesn't establish a connection between the cracking of the earth's crust and the occurrence of earthquakes. So, it doesn't strengthen the argument.

d) Severe earthquakes are generally caused by cracking of the earth's crust near the earthquake site.

- This answer choice establishes a connection between the cracking of the earth's crust and the occurrence of earthquakes. It suggests that the cracks in the earth's crust likely contributed to the earthquakes in Sweden. Therefore, it strengthens the argument and is the correct answer.

e) Asteroid impacts, which did occur at the end of the Ice Age, generally cause severe earthquakes.

- This answer choice provides an alternative cause for the earthquakes, which weakens the argument instead of strengthening it. So, it's not the correct answer.