The yellow background could be lit by another window or a different light source, so one could argue we don't have a good reference to tell. But the point is that the "picture of a thing" is not "the thing" itself, and there is always a possibility that they are different.

No, but it doesn't mean the other answer is invalid too. If there is no reference in the picture to tell what kind of light condition it was shot at, both answers could be possible.