Question

read the passage.
the evolving human skeleton
our early ancestors were hunter-gatherers who obtained food by hunting and by searching for edible wild plants. they needed strong bones, including large, strong jaws that enabled them to eat tough, uncooked foods. when our ancestors developed agriculture, however, their diet changed. they began growing plants, such as grains and beans, and raising animals for food; they also started cooking their foods, making them softer and easier to chew. consequently, the human skeleton underwent radical changes. over time, the human jaw became smaller and changed shape. other bones also evolved, becoming lighter, especially in the joints, as a result of both dietary changes and a less active lifestyle
what is the main, or central, idea of the passage?
early humans ate uncooked meats and vegetables, so they needed strong jaws for chewing.
as early humans developed agriculture, their bones changed significantly.

Explanation:

The passage first describes early human hunter-gatherer skeletons adapted to tough, uncooked food, then focuses on how the shift to agriculture (changed diet, cooked food, less active lifestyle) caused major changes to the human skeleton, including smaller jaws and lighter bones. The first option only covers a detail of the early hunter-gatherer stage, while the second captures the overarching, central change driven by agricultural development.

Answer:

As early humans developed agriculture, their bones changed significantly.