What are the four factors that must be present for natural
selection to act upon a population?

im not sure what your questions is about it could be

1) mutation, gene flow, genetic drift, and natural selection

or

2)reproduction, heredity, variation in fitness or organisms, variation in individual characters among members of the population.

Explanation:

a. as the temperature increases, the kinetic energy of the gas molecules increases & the molecules move faster & further away from each other.

b. if you decrease the temperature of a fixed amount of gas at constant pressure, the combined gas law reduces to charles's law. in this case, volume will also decrease.

that would be called plucking : )

explanation:

''plucking, also referred to as quarrying, is a glacial phenomenon that is responsible for the erosion and transportation of individual pieces of bedrock, especially large "joint blocks". as a glacier moves down a valley, friction causes the basal ice of the glacier to melt and infiltrate joints (cracks) in the bedrock."