D. Oxygen and metal
They usually contain some form of metallic cation, given that carbonates are the most distributed minerals in the Earth's crust.
Hope this helped!
Answer:
I believe your answer should be B.) Materials were pulled together by gravity. I hope this helps you!
Amphibia is the class of vertebrates which is considered to be the first to develop lungs. This allowed amphibians to live successfully on land as terrestrial organisms. Ichthyostega was the first primitive amphibians with nostrils and lungs. Amphibians adopted themselves to live on land with developed lungs.
