Ascientist finds what she thinks is a new species of rodent on a small pacific island. however, some similar-looking rodents inhabit some nearby islands. she mates the new rodent with the nearby rodents and gets viable but infertile offspring. why?
question 15 options:

the old and new rodents underwent vicariance, and their hybrid offspring were sterilized by adaptive radiation.

the new rodents probably derive from fairly recent ancestors that experienced dispersive allopatric speciation.*

the new and old rodents are both allopolyploid after undergoing sympatric speciation.

Option B

Explanation:

Dispersive allopatric speciation,  geographically move apart the population of any species  thereby restricting gene flow between the sub-populations  

These genetic difference accumulate and with time and cause genetic drift and variable selection pressures on the subpopulations.

This causes the separation up to an extent that even if the organisms from these two sub-populations are some how brought close to each other , they will yet not interact with each other and would remain two genetically distinct populations. The differences in mating preference and hybrid inferiority keep these sub-population separate from each other.  

Hence, option B is correct

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.