PrepTest 126

Incorrect. While it is noted that there were predators in grasslands and that humans may have needed to evolve bipedal motion to adapt to grassland, that doesn't mean that it was less hospitable than forests. Maybe the initial move to the grasslands was to a more hospitable environment that was made even more hospitable by later adaptations.

Correct. Argument or Facts:
Facts

Question Type:
Must Be True

Stimulus Summary:
Theories on the development of walking upright:
(1) When humans moved to grassland, to help with finding food and avoiding predators
(2) When humans still lived in dense forests, to help with gathering food on low branches
(3) To serve like an upright threat display, to help with finding a mate

Answer Anticipation:
This stimulus presents a phenomenon—the development of walking upright in humans—and then goes into three theories for what led to the development of it.

Normally, in a Must Be True question with several theories, the overlap between all of them ends up relating to the correct answer. However, there's no overlap between all of them—the closest shared feature is that two talk about food, but the third doesn't. The author doesn't take a side as to which is more or less likely. As such, it's almost impossible to form an anticipation of what to look for, so we'll have to head to the answer choices and use our framing to help us find the correct answer.

Answer Explanation:
This answer deals with the overlap between two of the three theories, so we should head back to the stimulus to see if there's enough information to support this answer. There, it's noted that in grasslands, walking upright would help find food; in dense forests, it would have helped find food. Since those are the two locations where humans are noted as living, there's support for this answer.

Key Takeaway:
When multiple theories are presented, not which—if any—the author agrees with. Also, identify how the theories are similar and different. These shared or divergent features are often key to finding the correct answer.

Incorrect. The information presented may be noncommittal as to whether walking upright developed to help humans survive in grasslands, but it's clear that it would be a benefit there—to both find food and avoid predators.

Incorrect. The author doesn't commit to any of the theories, so there's no support for this answer. She specifically notes that the "debate continues."

Incorrect. While the stimulus does note that bipedal motion would help in gathering food in both grassland and forest, and it only notes predation was a concern in grasslands, that doesn't mean it wasn't a concern in the forest. It also never ranks the importance of food vs. avoiding predators for survival, so this answer is unsupported.