To answer this question, we need to consider the information given. The house has four walls, and each wall faces south. There is also a window in each wall.
Since the walls face south, it implies that the house is located in the northern hemisphere. In the northern hemisphere, the sun typically shines from the south, meaning that the light would be coming from the north side of the house.
If the bear is walking by one of the windows, and the light is coming from the north side, it would cast a shadow on the bear. The color of the bear's fur is not mentioned, but we can infer that the bear's fur would appear dark or black due to the shadow cast by the light.
Therefore, the correct answer is A) Black.