Given the recent evidence suggesting that species change due to a certain genetic variations, what would be true? a) the theory was wrong.
b) natural selection cannot use evolution.
c) mutation and natural selection both cause changes in a population.
d) changes in a population occur abruptly as a response to the environment.

Asled is being held at rest on a slope that makes an angle θ with the horizontal. after the sled is released, it slidesa distance d1 down the slope and then covers the distance d2 alongthe horizontal terrain before stopping. find the coefficient ofkinetic friction μk between the sled and the ground, assumingthat it is constant throughout the trip. find the coefficient of kinetic frictionμk. express your answer in terms of someor all of the variables d1, d2, and θ.