The Next Few Questions Refer to the Following Description

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.
-Speculate on the most likely reason why two different species may be hybridizing more frequently than before.

A) There are too few male grizzly bears to mate with females, so females are mating with polar bears.
B) Female grizzly bears prefer the larger size of male polar bears.
C) Male polar bears are outcompeting male grizzly bears in coniferous forest habitats.
D) Grizzly bears are moving farther north to hunt seals and encounter polar bears.
E) With global warming, polar ice is melting, thus affecting the polar bears' hunting habitat and success; some hungry polar bears may be foraging further in the interior of the tundra and overlapping with foraging grizzly bears.