In general, characteristics that an organism survive and reproduce become more common in a population over time. what mechanism of evolution cause this change?

Natural selection.

Explanation:

Natural selection means that those with good phenotypes are more likely to survive and reproduce. On the other side of the same coin, organisms with less beneficial characteristics are less likely to survive. Because of this, they can't pass their genetic information down, making it less common, and vice versa.

i think its y= -4x-14