Question

psat 8/9 #1 reading & writing - part 1 dvor, brose, and their colleagues have described the factors that limit the maximum speeds that animals of different size can sustain. larger animals, all else being equal, can move faster than smaller animals because they can store more energy in their bodies and move farther with each stride. however, larger animals must also spend more of their travel time resting, because their bodies take longer to disperse the heat created by movement. the interaction of those two properties creates a hump - shaped curve, with animal speed increasing with size up to a certain point, then falling again for the largest animals. which choice best states the main idea of the text? a a larger animals stride is longer than a smaller animals, which is why size generally correlates with speed. b if smaller animals did not need to disperse heat by resting, they would be faster than larger animals. c an animals size affects its movement and metabolism, which in turn determine its maximum speed. d large animals move more slowly than small animals because their heavy bodies require more energy to move.

Explanation:

The text discusses how factors like stride, heat - dissipation, and body size affect the movement speed of animals. It mentions that larger animals can move faster due to longer strides and energy - storage capabilities up to a point, and then speed decreases as size increases further. Option A best captures the main idea about the relationship between animal size and stride related to speed.

Answer:

A. A larger animal's stride is longer than a smaller animal's, which is why size generally correlates with speed.