If You Analyzed the Chemical Composition of a Tree Branch

Multiple Choice

If you analyzed the chemical composition of a tree branch and the leg of a cow, you would find a similar proportion of carbon, hydrogen, oxygen and nitrogen. What is the best explanation for this observation?

A) Cows and trees are closely related species.
B) Other elements must be present that account for the differences seen in the tree and cow.
C) The tree branch and leg of the cow must have similar functions and thus be homologous structures.
D) The organization of the atoms in the tree and cow account for differences between these species.
E) The chemicals that make up an organism are not important, any chemicals could be used.