For each of the following examples, discuss whether it would be the result of neutral mutations or mutations that have been acted on by natural selection, or both:
A. When comparing sequences of homologous genes, differences in the coding sequence are most common at the wobble base (i.e., the third base in each codon).
B. For a protein-encoding gene, the regions that encode portions of the polypeptide that are vital for structure and function are less likely to display mutations than other regions of the gene.
C. When comparing the sequences of homologous genes, introns usually have more sequence differences than exons.