From the passage about the transformation of western Kansas, what factor does the author say changed the entire landscape of Kansas?

Introduction / Context:
This question focuses on a factual detail from the passage. The author compares the relatively unchanged arid West with western Kansas, which has undergone drastic change. You must identify the specific cause of this change as stated by the author.

Given Data / Assumptions:
• The author says that western Kansas has been torn up by agriculture.
• The flat plains, excellent soil and just adequate rainfall are mentioned as reasons why farming became possible.
• The result is that about ninety percent of the original sod prairie is gone.
• No mention is made of wind, heat or flooding as causes of this large-scale transformation.

Concept / Approach:
The skill involved is locating key factual statements and distinguishing them from background description. The phrase torn up by agriculture directly attributes the change to human farming activity, not to natural forces.

Step-by-Step Solution:
Step 1: Identify the part of the passage that talks about change in the landscape. Step 2: Note the explicit statement that western Kansas has been torn up by agriculture. Step 3: Connect the disappearance of ninety percent of the sod prairie with agricultural development. Step 4: Confirm that other natural factors like wind, heat or flooding are not blamed for this major change. Step 5: Select agriculture as the factor that changed the entire landscape.

Verification / Alternative check:
If agriculture were removed from the passage, the main explanation for the loss of prairie would disappear. None of the other listed options are mentioned, so they cannot be the correct answer.

Why Other Options Are Wrong:
Wind: Although wind can shape plains, the passage does not refer to it as a destructive force here.
Heat: Heat is a feature of climate but is not described as a cause of landscape destruction in the text.
Flooding: No floods are mentioned at all; this option introduces information not present in the passage.

Common Pitfalls:
Some candidates overthink and assume natural disasters caused the change, but the passage clearly emphasises human activity, especially agriculture, as the main agent of transformation.

Final Answer:
The correct answer is agriculture, because the author states that western Kansas has been torn up by agriculture, leading to the loss of most of the original prairie landscape.