True or false our atmosphere is very thin compared to the size of the Earth?

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.

Is dna the same in every cell in the human body explain your answer

An area has a few days of low humidity, warm air temperature, and high air pressure. what kind of weather is this area experiencing? o fog o snow storms o sun