The Earth's mantle flows in circles, causing tectonic plates to move. What is an effect of these moving plates? A Intense heat flows from the Earth's core.

В The atmosphere acts like a giant blanket.

C Gases are released into the atmosphere.

D Volcanoes are created.​

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.