Which best describes how an ionic bond forms?
a. one atom pulls an electron from another atom.
b. two atoms both lose an electron.
c. two molecules share an electron.
d. two atoms share valence electrons

Which of the following factors would not contribute to allopatric speciation? a) a population becomes geographically isolated from the parent population.b) the separated population is small, and genetic drift occurs.c) the isolated population is exposed to different selection pressures than the ancestral population.d) different mutations begin to distinguish the gene pools of the separated populations.e) gene flow between the two populations is extensive.