Scientists observe a population of squirrels over a long period of time. The scientists note that after the populations are able to live together, the black and the brown squirrels are not able to produce fertile offspring. Which explanation best supports the scientists’ observation? A. The squirrel population experienced more mutations living together than living.
B. The squirrel population did not have enough genetic variation to produce fertile offspring.
C. The squirrel population divided into dominant population and a recessive population of one species.
D. The squirrel populations on either sid eof the river did not experience gene flow and became two different species.

I think answer B is correct

condensation. good luck!

cells use diffusion to get substances in and out of themselves. that diffusion will occur across the cell membrane or the outer covering of the cell. because we are talking about the surface of the cell, surface area and volume are  important factors here. as a cell increases in size, its surface area and volume increase as well.  we call that the surface area to volume ratio (sa: vol).  but the catch is that  volume increases at a greater rate than surface  area. in other words, as a cell gets bigger, the sa: vol gets smaller. so a really small cell like bacteria is mostly cell membrane (surface) with very little contents (volume). a really big cell like an egg, is mostly insides with a super thin membrane. so what ends up happening is that the cell cannot efficiently diffuse all of the stuff it needs in/out to survive. therefore cell size is limited to about 100mm. so how do we make organisms bigger than 100mm? cells divide! by dividing and becoming multicellular, organisms are able to grow!   check out the diagrams i attached to see the effect of sa: vol. i hope this ! good luck!