If Two Species Are Able to Mate and Produce an Offspring

Multiple Choice

If two species are able to mate and produce an offspring which can mate with itself,but which is unable to mate with its parent's species then this can best be described as an example of

A) allopatric speciation.
B) sympatric speciation via disruptive selection.
C) sympatric speciation via polyploidy.
D) a species cluster.
E) character displacement.