LSAT Explanation PT 37, S4, Q25: In ancient Mesopotamia, prior to 2900

LSAT Question Stem

Which one of the following, if true, most helps to support the historians' contention concerning the reasons for the decline in wheat production in ancient Mesopotamia? 

Logical Reasoning Question Type

This is a Strengthen question. 

Correct Answer

The correct answer to this question is B. 

LSAT Question Complete Explanation

Let's first analyze the argument presented in the passage. The argument states that in ancient Mesopotamia, wheat production declined after 2900 B.C. as barley production increased. The historians contend that the decline in wheat production was due to three factors: 1) excessive irrigation, 2) lack of drainage, and 3) the consequent accumulation of salt residues in the soil. The conclusion of the argument is that these three factors caused the decline in wheat production.

Now, let's create an "Evaluate" question for this argument: "How does the accumulation of salt residues in the soil affect wheat and barley differently?"

The question type for this problem is Strengthen, which means we are looking for an answer choice that helps support the historians' contention about the reasons for the decline in wheat production.

Let's evaluate each answer choice:

a) The cultivation of barley requires considerably less water than does the cultivation of wheat.

This answer choice might seem tempting because it suggests that barley's lower water requirement could have contributed to the shift from wheat to barley. However, this doesn't address the main issue of salt accumulation in the soil, which is the primary cause of the decline in wheat production according to the historians. Moreover, the passage mentions that there was excessive irrigation, so water availability is not the main concern.

b) Barley has much greater resistance to the presence of salt in soil than does wheat.

This answer choice directly addresses our "Evaluate" question and supports the historians' contention. If barley is more resistant to salt in the soil than wheat, it would explain why the accumulation of salt residues led to a decline in wheat production and an increase in barley production. This is the correct answer.

c) Prior to 2900 B.C., barley was cultivated along with wheat, but the amount of barley produced was far less than the amount of wheat produced.

This answer choice provides information about the production of barley and wheat before 2900 B.C., but it doesn't help explain why wheat production declined after 2900 B.C. due to the factors mentioned in the passage.

d) Around 2900 B.C., a series of wheat blights occurred, destroying much of the wheat crop year after year.

This answer choice weakens the argument by presenting an alternative explanation for the decline in wheat production. It doesn't support the historians' contention that the decline was due to excessive irrigation, lack of drainage, and salt accumulation.

e) Literary and archaeological evidence indicates that in the period following 2900 B.C., barley became the principal grain in the diet of most of the inhabitants of Mesopotamia.

This answer choice merely restates the fact that barley production increased after 2900 B.C. but doesn't explain why wheat production declined due to the factors mentioned in the passage.

In conclusion, the correct answer is B, as it directly addresses the "Evaluate" question and supports the historians' contention about the reasons for the decline in wheat production in ancient Mesopotamia.