What is the name for the underground layer of permeable rock that contains water

*will mark brainliest* certain species of are now recognized as indicators of environmental pollution. a. lichen b. mushroom c. yeast d. none of the above

How had the study of mitosis affected scientists knowledge of cancer

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.