As the biological hierarchy is moved through from the kingdom level down to the species level, do organisms... *
A. Vary more and more
B. Become more similar to each other

Asquirrel population lives in an area. over many years, a river in that area grows wider and stronger, eventually forming a canyon. the squirrel populations on the two sides of the canyon can no longer mate with each other and ultimately form distinct species. this is an example of