What is one observation that could be made to support the idea that two rock layers are the same age?

A. layers with different fossils

B. layers of equal density

C. layers made of the same chemicals

D. layers with similar fossils

Part a - which gene to compare? in this exercise, you will use the cytochrome c oxidase i (coi) gene to investigate relationships among salmon species. (this gene encodes a protein that functions in the mitochondrial electron transport chain.) you will compare the coi gene sequences from your salmon test samples to the standard sequences for each salmon species. in order for the coi gene to be useful for distinguishing among the different salmon species, which three statements must be true?