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?
as early humans developed agriculture, their bones changed significantly.
early humans ate uncooked meats and vegetables, so they needed strong jaws for chewing.

Explanation:

The passage starts by describing early hunter - gatherer ancestors' need for strong bones due to their diet. Then it shows how the development of agriculture led to dietary changes (cooking, new food sources), which in turn caused significant changes in the human skeleton like a smaller jaw and lighter bones. The first option captures this overall transition related to agriculture and bone changes, while the second option only focuses on the early hunter - gatherer diet aspect.

Answer:

As early humans developed agriculture, their bones changed significantly.