In order for natural selection to change a trait within a population, what must be true about the trait?

Based on the evidence in the excerpt above, describe in your own words what it would have been like for a person to enter a meat processing plant in the united states

Sara goes on a slingshot ride in an amusement park. she is strapped into a spherical ball that has a radius 3*10^2 of centimeters. what is the volume of air in the spherical ball? use this formula: volume of a sphere=4/3pi, r^3 , where r is the sphere’s radius.

What does the hardy-weinberg principle relate to? a. chances of survival of an organism b. frequency of alleles in a population c. natural selection in a species d. causes of evolution among organisms