A. is the correct answer bc a mutation changes the DNA.
Geographic Isolation Because i had bio last year an i remember that Exact Question
<em>Answer</em><em>:</em><em>Nitrogen fixation</em><em> </em><em>is</em><em> </em><em>the</em><em> </em><em>nitrogen</em><em> </em><em>fixing</em><em> </em><em>bacteria</em><em>.</em>
The best answer would be "research reasons why species change over long periods of time"
if not i apologize but this is my best guess<span />