Answer:
B
Explanation:
The answer is asking which change would lead to better survival rates of darker moths. These moths survive because they can blend in with the environment, like the lighter moths on the birch trees. In order for the darker moths to be more likely to survive, they would need to blend in. B is the only option in which the trees become darker, making it easier for the dark moths to blend in and thus, survive.
Note that option D would only inhibit the survival of the white moths, not help the dark ones, and the other two options have nothing to do with the moths or coloration.
