In most organisms, macromolecules play a central role as the energy source. This macromolecule must be transformed in the body to produce the usable energy molecule . Interestingly, this energy molecule is a type of macromolecule. A
carbohydrate, adenosine triphosphate, nucleic acid

B
lipid, atropine tetraphosphate, protein

C
protein, adenosine triphosphate, lipid

D
carbohydrate, atropine triphosphate, protein

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.