Answer:
Mammals give live birth to their offspring. Reptiles and amphibians lay eggs. Mammals are also usually warm blooded while reptiles and amphibians are cold blooded. Most amphibians and reptiles abandon their young at a certain age while most mammals will take care of their offspring forever.
Explanation:
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The second option: meiosis and fertilization
process A is meiosis, you can see that the gamete(haploid cell) results from the diploid cell. The gamete has n chromosomes(39), whereas the diploid cell has 2n(78)
process B is fertilization the two gametes(haploid) fuse together to form the zygote(diploid)
Because it’s good for the environment to have a good balance and not to much of one thing