Logical reasoning PrepTest 138 · Section 3 · Question 2

Incorrect. White-footed mice thrive in fragmented forests, but that doesn't mean they don't exist in other forests. They may be present in almost all forests, just at a much higher level in fragmented ones.

Incorrect. The stimulus talks about "[s]ome animals" including a certain type of mice thriving in fragmented forests. That's not nearly a strong enough statement to support this answer about "most" small animals.

Incorrect. The stimulus never discusses a reduction in species as a result of forest fragmentation, just that certain animals thrive.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Forest fragmentation = breaking a forest into smaller patches
Forest fragmentation causes white-footed mice to thrive
White-footed mice are the primary vector for Lyme disease

Answer Anticipation:
These statements have a lot of overlap between them, but they're not conditional. They are, however, causal, and we can chain causal statements together as much as we can conditional ones.

The stimulus notes that forest fragmentation causes white-footed mice to thrive, which increases a potential source of Lyme disease in humans. Therefore, we can say that forest fragmentation increases the risk that humans will get Lyme disease.

Unlike conditional statements, causal statements can be inverted, to a certain degree. So if it's true that forest fragmentation can increase the incidence of Lyme disease, then it's also true that stopping forest fragmentation can be a factor in fighting Lyme disease.

Answer Explanation:
This answer reflects the causal relationship that could be inferred from the stimulus. Forest fragmentation can cause white-footed mice to thrive, which threatens human health in the form of Lyme disease. Therefore, stopping forest fragmentation can fight a causal factor in Lyme disease, thus benefiting human health.

Key Takeaway:
Like conditional statements, causal statements can chain together. Unlike conditional statements, causal statements can be inverted—if the cause is taken away, it should reduce the effect.

Incorrect. The stimulus doesn't discuss tick population density. While it does imply that ticks are present in fragmented forests, thus transmitting Lyme disease to humans, that doesn't require them having their "highest" population density in such forests. Their population could be equally dense as in other forests, but the higher number of white-footed mice makes it easier to pick up Lyme disease.