Yes you can. The atomic mass measured from the proteins and neutrons in an atom, since you know he number of protons, you can subtract and be left with the number of neutrons.
The answer your looking for is 20 Amino Acids.<span>
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The correct answer is (a.) a mutation of the hemoglobin allowing better oxygen-carrying capacity. The mutation of the hemoglobin that allows a better oxygen-carrying capacity would be the most beneficial to an elephant and its descendants.