The correct answer is D.
The domain is the broadest category in the classification of living organisms. All the living organisms are placed in three domains, which are archaea, bacteria and eukaryotes. The prokaryotes are separated into two groups, that is archaea and bacterial based on the differences in their 16S rRNA genes. Amoeba is classified as an eukaryotes because, its cell is more developed than that of bacteria.
I'm pretty sure your talking about Vertebrates
Is a written representation of something.
The basic structure of bones is bone matrix, which makes up the underlying rigid framework of bones, composed of both compact bone and spongy bone. The bone matrix consists of tough protein fibers, mainly collagen, that become hard and rigid due to mineralization with calcium crystals.
