Question

Initially, the myrtle warbler and Audubon's warbler were considered two different species. These birds have now been reclassified as eastern and western forms of a single species. Which of the following pieces of evidence would warrant this reclassification?
A. The two forms interbreed successfully where their habits overlap.
B. The two forms live in habits with similar terrain and temperatures.
C. The two forms eat the same type of wood grubs and flying insects
D. The two forms display very similar physical traits such as coloration and tail-shape.

Answer 1

Just figured out that it's answer A for anyone else with the same question.