The correct answer is A. Under a full moon; the owl caught more dark mice when there was no moon (about 20) than when there was a full moon (about 12).
This data suggests that dark brown mice have a better chance of evading predation under a full moon compared to having no moon, as the presence of moonlight may make it more difficult for the owl to spot them against the dark soil. The fact that more dark mice were caught when there was no moon emphasizes that the moonlight may provide a slight advantage for these mice to blend into their environment and avoid predation.