Which characteristic of four different dinosaur fossils makes a dinosaur most similar to the present-day birds?

1. Hollow bones. Like present day birds most if not all dinosaurs had hollow bones.

2.Quill knobs. Quill knobs are small bumbs in the wings of birds where primary flight feathers are, although most non avian dinosaurs couldnt fly, some such as concavenator, velociraptor, dakotaraptor, and many more have these quil knobs where feathers are likely to be.

3. Wishbone. Many theropod dinosaurs including the mighty tyrannosaurus rex, had a wish bone just like the birds of today.

4. Structure. Even though it may not be entirely obvious, birds have tiny tails, feathers are attached to those tails. The tail of birds are simulure to dinosaurs, the only difference being size. Not only that, but both birds and dinosaurs have a reversed first toe.

Hope this helps.

Explanation:

the speed increase from w to x due to increased gravity force

the speed decreases from x to y due to decrease in gravity

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."