The answer is A. Under a full moon; the owl caught more dark mice when there was no moon (about 37) than when there was a full moon (about 19).
This data suggests that a dark brown mouse on dark-colored soil is more likely to escape predation under a full moon, as fewer dark mice were caught during that time compared to when there was no moon. This implies that the increased light from the full moon makes it more challenging for the owl to effectively hunt dark-colored mice against a dark background.