a certain species of butterflies gradually becomes darker. the birde in the same area feed on the white or lightly colored buterflies, ;eaving tuterflies that are dar colore. what type of selection

Natural selection.

Explanation:

The dark colour butterflies will increase in their population due to favourable conditions of the surrounding environment. They are naturally selected by the nature due to their suitability and compatibility with the environment that allows dark butterflies to increase in their population. The colour of dark butterflies helps them to not eaten by the predators that allows them to increase in their population so we can say that this type of selection is natural selection.

x would be the most and the least would be y because there are more fruit   and seeds than flock z has insects