The Next Few Questions Refer to the Following Description

Multiple Choice

The next few questions refer to the following description:
Fossil evidence suggests that polar bears, Ursus maritimus, arose from grizzly bears, Ursus arctos. On average, polar bears are slightly larger than grizzly bears in size and weight. The morphological features/adaptations of polar bears make them well suited to survival in a marine environment. Interbreeding and production of fertile offspring between the two species has been recorded in captivity, and more recently in the wild.
-The biological species concept emphasized the absence of gene flow. Which alternative species concept(s) is(are) applicable to explaining the hybridization between grizzly and polar bears?

A) the morphological species concept, since it puts emphasis on similarities between the two species
B) the ecological species concept, as it addresses organisms' adaptations to changing environmental conditions
C) the allopatric species concept, since it emphasizes geographical barriers
D) A, B, and C
E) all except C