Comparing the body structures of organisms to find evidence of a shared evolutionary history

That is the definition of Comparative anatomy. This study is focused on similarities and differences in the anatomy of different species. It is closely related to evolutionary biology and phylogeny which is part of the large study of the evolution of species. This study is useful because it helps to determine evolutionary relationships between organisms and whether or not they share common ancestors. 

The answer is c water is the solvent and salt is the solvent

Alright, i'm gonna try to explain this as good as possible. the law of conservation is like a collection overtime. it never changes though. no matter how you change the constituent parts.