A Little Girl Notices That She Has a Male Dog

A little girl notices that she has a male dog and a female cat in her house at the same time. The dog and cat are the same size, and they seem friendly enough. Why don't these two animals ever mate?

A) Because the dog and cat are temporally isolated from each other.
B) Because the dog and cat are ecologically separated from each other.
C) Because the dog and cat are behaviorally isolated from each other.
D) Because the dog and cat are allopatric species.
E) Because the dog and cat are peripatric species.