How a magnifying glass can a scientist?

Acid rain is the direct result of acid released by burning fossil fuels. select the best answer from the choices provided ot o f true or false

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.

The diagram shows the development of the oocyte and the follicle during the menstrual cycle. identify at which stage in the cycle the hormone levels are at their highest and most active.