What evidence supports a scientist's conclusion that fossil b is older than fossil a?

Which number is main idea? i need answer quick. (1) people may think that love and romantic feelings are enough of a basis for choosing a spouse. (2) the chances of a marriage surviving, however, would improve if prospective marriage partners considered a few unromantic questions before deciding on matrimony. (3) for example, do the two individuals involved share a common socioeconomic background? (4) the more similar they are in their social, economic, religious, and cultural backgrounds, the more similar their expectations about married life will be. (5) in addition, what are their goals? (6) it’s a big advantage to the marriage if they know and share one another’s goals concerning career, lifestyle, and family. (7) finally, and maybe most important, how does the prospective spouse treat others in his or her life? (8) during the courtship, the boyfriend or girlfriend may get special consideration, but in the long run, spouses will probably treat each other about the same way they treat their own family members.

In the image, layer a is the topmost layer. layer c contains fossils from the precambrian era. layer b contains dinosaur fossils, and layer a contains fossils of mammals. which two statements are supported by this evidence? 1. mammals lived before the precambrian era. 2. dinosaurs and mammals existed in the precambrian era. 3. dinosaurs evolved after precambrian organisms. 4. precambrian organisms evolved after dinosaurs. 5. precambrian organisms were the first life-forms to become fossilized, according to this sample.

Snakes, dogs, and humans have a vertebral column. snakes and dogs have tails, and humans have vestigial tailbones. dogs and humans have limbs, but snakes do not. most reptiles lay eggs, but a few give birth to live young. what do these structures suggest about the evolutionary pattern between the three organisms? 1. snakes and dogs are more closely related than snakes and humans. 2. snakes and humans are more closely related than humans and dogs. 3. dogs and humans are more closely related than snakes and humans. 4. dogs, snakes, and humans share a common ancestor. 5. the early ancestor of snakes and dogs is the same, and the early ancestor of humans is different.