The correct answer is "1 = Birds, 2 = Mammals, 3 = Amphibians".
Explanation:
The table shows characteristics of three different classes of organisms. The first class corresponds to birds since they are warm-blooded animals with hollow bones, which build nests for their progeny and reproduce by nesting thin-shelled eggs. The second class belong to mammals, with four-chambered hearts (right atrium, left atrium, right ventricle and left ventricle), which nurses young for their survival and have hair or fur. The third class corresponds to amphibians, which lay eggs in water, have thin skin and perform metamorphosis (for instance, the frogs that transform from tadpoles to adult frogs). I attached the missing table.
Atoms come together to form molecules because of their electrons. Electrons can join (or bond) atoms together in two main ways. When two atoms share electrons between them, they are locked together (bonded) by that sharing. These are called covalent bonds
