Question

birds and dinosaurs
though we think of dinosaurs as being extinct, recent research suggests that their modern relatives live among us in the form of birds. like birds, many dinosaurs built nests, laid eggs, and had feathers. over the last twenty years, scientists have collected more and more evidence suggesting that dinosaurs evolved into birds. for example, thousands of fossils of dinosaurs with feathers have been found in china, and fossilized dinosaur eggs are similar in size and shape to birds eggs. fossils have also revealed information about dinosaurs skeletons. birds have hollow bones to enable flight, and so did some dinosaurs. in addition, birds and dinosaurs exhibit many similarities in their legs, feet, and claws.
what is the main, or central, idea of the passage?
fossil evidence shows that dinosaurs and birds share many features, suggesting that they are related.
fossil evidence shows that the legs, feet, and claws of dinosaurs and birds are similar.
fossil evidence shows that some dinosaurs had hollow bones, which probably enabled them to fly.

Explanation:

The passage lists multiple fossil - based similarities between dinosaurs and birds like feathers, egg - shape, hollow bones, and leg/foot/claw features to suggest a relationship. The first option encompasses all these aspects as the main idea, while the other two are just specific details.

Answer:

Fossil evidence shows that dinosaurs and birds share many features, suggesting that they are related.