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Critical Reasoning: Conclusion Strengthening Questions

The Takuur Swamp frog is well-known mainly due to the peculiar protrusion that appears on the top of its head. Archaeological findings show that the Takuur and its evolutionary ancestor are almost identical, except for the ancestor's slightly larger protrusion. Originally believed to be decorative, research being performed by a team of zoologists is leading them to believe that the protrusion belonging to the Takuur's ancestor was used by the frog to swat insects on which it fed.

Which of the following, if true, most strongly supports the zoologists' belief?

Incorrect.

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This answer choice presents evidence that neither strengthens nor weakens the zoologists' hypothesis. The fact that the Takuur and its ancestor have similar reproductive patterns has nothing to do with how it caught its prey.

Incorrect.

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This answer choice presents evidence that neither strengthens nor weakens the zoologists' hypothesis. The fact that the earth was once covered by more swamps than it is today does not help us strengthen the claim that the Takuur used its protrusion to kill flies.

Incorrect.

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This answer choice neither strengthens nor weakens the zoologists' hypothesis. The fact that some animals have decorative body parts does not necessarily mean this applies to the Takuur (and if it did, it would weaken the zoologists' conclusion).

Incorrect.

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This answer choice weakens the zoologists' hypothesis. If the takuur fed almost entirely on algae, then it probably would not have developed a specialized body part just to kill flies. Focus on the zoologists' belief - you should be trying to find a statement that can strengthen it.

Very well done!

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This answer choice does strengthen the zoologists' hypothesis by presenting us with a physical clue about the Takuur. Since it can move its protrusion accurately and at great speed, and since it is similar to its ancestor, it seems quite logical to infer that the protrusion may have been used, and not just for decoration.

Evidence shows that the present-day Takuur and its ancestor have extremely similar reproductive patterns.  
In certain prehistoric periods, the earth's surface was covered by almost 30 times more swamp area than it is today.
The Takuur's ancestor spent most of its time in the water and fed almost entirely on algae.
The animal kingdom offers a number of examples of decorative body parts which are used mainly for mating and the establishment of social status.
The present-day Takuur's protrusion contains a strong muscle that could easily allow it to be moved at great speed and with accuracy.