Out of the following given choices;
a) small groups immigrated from a single original population
b) the populations adapted in different ways to local conditions
c) the species original habitat became increasingly rare over time
The answer is B. Vicariance occurs when parts of the population become physically isolated from other parts of the population leading to allopatric speciation of the population. Allopatric speciation occurs respective parts of the population adapt to local conditions while mating in the entire population is inhibited by the geographical separation.
